Xiao Hong read a story book. On the first day, she read 30 pages, which is exactly 2 / 7 of the book. On the second day, she read the remaining 3 / 5 of the book. On the third day, what page should we start from?

Xiao Hong read a story book. On the first day, she read 30 pages, which is exactly 2 / 7 of the book. On the second day, she read the remaining 3 / 5 of the book. On the third day, what page should we start from?

30 / 2 / 7 = 105 pages, so there are 105 pages in this book
(105-30) × 3 / 5 = 45 pages, I read 45 pages the next day
105-30-45 + 1 = 31 pages
A: the third day should start from page 31
30 / 2 / 7
=30 * 7 / 2
=15*7=105
105-30=75
75 * 3 / 5
=15*3=45
75-45=30
A said, "my number is half of the sum of the three of you."
B said, "I have one third as many books as the three of you."
C said, "I have one third as many books as the three of you."
Ding said, "I have 260 copies."
Who has the most books
Suppose that a, B and C have books a, B and C respectively, 2A = B + C + 260. (1) 3B = a + C + 260. (2) 3C = a + B + 260. (3) (1) - (2) get 2a-3b = b-a3a = 4BB = 3A / 4 (2) - (3) get 3b-3c = c-b4b = 4CB = C, then C = b = 3A / 4 with C = b = 3A / 4 into (1) get 2A = 3A / 4 + 3A / 4 + 260a / 2 = 260a = 5
The sum of all the digits of a nine digit number is 140000, of which the number of ten thousand digits is three times that of one digit number. What should be the maximum and the minimum of the nine digits
Maximum 320090000
Minimum 100030019
The maximum is 430080000 and the minimum is 100020039.
These nine numbers can only be 0,1,2,3,4,5,6,7,8,9, and the number on the ten thousand bit is twice that on the hundred million bit. Find the ones with double relationship from the middle: 1 and 2,2 and 4, 4 and 8. If you want to get the nine digit number, the key lies in the hundred million digit number, so the hundred million digit number is 40, and the ten thousand digit number is 8. The sum of these two numbers is 12, and there is another three, which is the largest in the hundred million digit number,. If you want to be the smallest, it's 10000 in 100 million, it's 2 in 10000, it's 3 in total, 15-3 = 12, there are 12, just said... Expand
The maximum is 430080000 and the minimum is 100020039.
These nine numbers can only be 0,1,2,3,4,5,6,7,8,9, and the number on the ten thousand bit is twice that on the hundred million bit. Find the ones with double relationship from the middle: 1 and 2,2 and 4, 4 and 8. If you want to get the nine digit number, the key lies in the hundred million digit number, so the hundred million digit number is 40, and the ten thousand digit number is 8. The sum of these two numbers is 12, and there is another three, which is the largest in the hundred million digit number,. If you want to be the smallest, 10000 bits in 100 million bits are 2, which add up to 3,15-3 = 12, and 12. As I said just now, these nine numbers can only be 0,1,2,3,4,5,6,7,8,9, so 12 can be divided into 3 and 9,4 and 8,5 and 7,6 and 6. Take the minimum, 3 and 9, but put 3 on the tenth place to get the minimum. Question: ten thousand is three times as many as one hundred million
A story book has 150 pages. Xiaoling read one fifth of the book on the first day, and two fifths of it on the second day. Xiaoling read two fifths of the book on the second day
Back: how many pages did Xiao Ling read in two days? (equation) write down the equivalent relation
150*(1/5)+150*(2/5)=30+60=90
A simple method of solving a mathematical problem (process)
3.6x31.4+43.9x6.4
20.05x39+200.5x4.1+40x10.05
3.6x31.4+43.9x6.4=3.6x31.4+31.4x6.4+12.5x6.4=31.4x(3.6+6.4)+12.5x8x0.8=314+100x0.8=314+80=39420.05x39+200.5x4.1+40x10.05 = 20.05x39+20.05x41+40x20.05-40x10=20.05x(39+41+40)-400=20.05x120-400=2005+20.0...
For a nine digit number, the sum of the numbers in each digit number is 150000. The number in 10000 digits is twice that in 100 million digits. The maximum number is 150000______ The smallest is______ .
If you want to make this number large, you can make the number of hundred million bits 4, then ten thousand bits is 4 × 2 = 8, ten million bits is 15-4-8 = 3, and the rest are 0, that is 430.8 million; if you want to make this number small, you can make the number of hundred million bits 1, ten thousand bits is 2, and there are 15-1-2 = 12 left, so divide it into
Mathematics read a story book. On the first day, I read two fifths of the whole book. On the second day, I read one ninth of the whole book
Reading a story book, I read two fifths of the whole book on the first day, one ninth of the whole book on the second day, and I read 16 pages less on the second day than on the first day. How many pages of this book
16÷（2/15-1/9）＝16÷（6/45-5/45）＝16÷1/45＝720
The answer is 720 pages
Page x
2X/15-X/9=16
X=720
16÷（2/15-1/9)
=16÷（6/45-5/45)
=16*45
=720 pages
A simple method to calculate the formula (1) 5 out of 9 + 5 out of 17 + 4 out of 9-5 out of 17 (2) 2x14 out of 5 + 2 out of 5
(1) 5 / 9 + 5 / 17 + 4 / 9-5 / 17
=(5 / 9 + 4 / 9) + (5 / 17-5 / 17)
=1+0
=1
(2) 2x14 / 5 + 2 / 5
=2 / 5 x (14 + 1)
=2 / 5 × 15 5 and 15
=6
A 9-digit number. The sum of the numbers in each digit is 150. The number in 10000 digits is twice that in 100 million digits. What is the maximum number and what is the minimum number
The maximum is 430080000
The minimum is 100020039
A story book has 180 pages. Xiao Li read 1 / 3 of the total pages on the first day, 45 pages on the second day, and how many parts of the book are left to read? If the rest of the book is finished on the third day, what is the simplest integer ratio of the pages read in the three days?
I read 180 * 1 / 3 = 60 pages on the first day, and 45 pages on the second day
There are still 180-60-45 = 75 pages left, accounting for 75 / 180 = 5 / 12
That is, the remaining 5 / 12 of the book did not read
The simplest integer ratio of the number of pages viewed in three days is 60:45:75 = 4:3:5