Xiao Gang read a story book. On the first day, he read 72% of the whole book. On the second day, he read 13% of the whole book. There are 60 pages left?

The remaining 60 pages are 15% of the book, so 60 divided by 15% equals 400 pages

Xiao Gang has a science and technology book with a total of 60 pages. He read 15% of the whole book on the first day and 60% of the whole book on the second day. How many pages did he read in two days?

60 × (15 + 60%), = 60 × 0.8, = 48 pages; a: 48 pages in two days

If a three digit number is divided by 37, the remainder is 17, divided by 36, and the remainder is 3, what are the three digits

37m+17=36n+3
36n-37m=14
36(n-m)-m=14
Let N-M = 1
Then M = 22
n=23
36n+3=36×23+3=831
This three digit number is 831

The sum of the first n terms of the sequence {an} is Sn, and Sn = (n ^ 2 + 3n) / 2 is known
If the sequence {CN} satisfies C (n) = a (n) (n is odd), C (n) = 2 ^ n (n is even), the sum of the first n terms of the sequence {CN} is TN, and TN is obtained when n is even
The answer is TN = ((n ^ 2 + 2n) / 4) + ((4 / 3) ((2 ^ n) - 1)),

X divided by 2 plus 40 divided by x equals 9 ask how much x equals? How to calculate

X／2＋40／X＝9
X²／2X＋80／2X＝9
X²＋80＝18X
X²－18X＋80＝0
X＝[18±√﹙18²＋4×80﹚]／2
X1＝﹙18＋2﹚／2＝10
X2＝﹙18－2﹚／2＝8

If the solution of the equation 2x + 3 = 1 / 3-m about X is x = - 2, then the value of 1 / 2 of M-M is

x=-2
Then - 4 + 3 = (1-m) / 3
1-m=-3
m=4
So 1 / 2 of M-M = 4-1 / 16 = 63 / 16

1 / 16 () = 75% = (): 12 = () 40

16 (12) = 75% = (9): 12 = (30) / 40
Do not understand can ask, help please adopt, thank you!

Finding positive integer solutions of equations x + y = k, 5x + 3Y = 26
It's hard

If 5x + 3Y = 26, then x = (26-3y) / 5. Since x is a positive integer, then 26-3y should be a multiple of 5, so y = 2, 3 and 7. At this time, the corresponding values of X are 4, 3 and 1 respectively, so k = 6 or 8

（-9.18）×（-0.28）÷（-10.71）=?
I know the answer is 0.24, but how do you work it out

（-9.18）×（-0.28）÷（-10.71）
=9.18x28/1071
Start to make an appointment
=9.18x4/153
=0.54x4/9
=0.06x4
=0.24

How to find the area of square, rectangle, triangle, trapezoid and parallelogram

Square area = square of side length
Rectangle area = length x width
Triangle area = base x height △ 2
Trapezoid area = (upper bottom + lower bottom) x height △ 2
Area of parallelogram = side length x height

Xiao Gang read a story book. On the first day, he read 72% of the whole book. On the second day, he read 13% of the whole book. There are 60 pages left?