If 400 science and technology books are replaced by story books, the number of story books is three times that of science and technology books. If 100 story books are replaced by science and technology books, the number of story books is 5 / 11 of science and technology books? It's better not to make equations Other solutions to write a good formula to explain the meaning!

If 400 science and technology books are replaced by story books, the number of story books is three times that of science and technology books. If 100 story books are replaced by science and technology books, the number of story books is 5 / 11 of science and technology books? It's better not to make equations Other solutions to write a good formula to explain the meaning!

First of all, it should be clear that no matter how to change the total number, the number of story books will remain unchanged. If the number of story books is reduced by 100 and the number of science and technology books is increased by 100 (the result of the second case), then the number of story books will account for 5 and the number of science and technology books will account for 11. In this case, the number of story books will be 5 / (11 + 5) = 5 / 16 of the total number; if the number of story books is increased by 500, the number of science and technology books will be reduced by 500 (the first

The linear equation with slope k of 2 and intercept - 3 on Y axis is

y=2x-3

1.49+499+4999+49999+4999
1.49+499+4999+49999+499999； 2.（1+11+21+31+41）＋（9+19+29+39+49） 3.（9999+9997+1995+…… +9001）－（1+3+5+…… +999 ） 4.123+234+345+456+5657+678+789 5.1400÷25÷8+350÷4÷125 6.9÷13+13÷9+11÷13+14÷9+6÷13
6.（0.36×5.1×81）÷（0.17×8.1×0.4）
Write all six

1
49+499+4999+49999+499999
=（50+500+5000+50000+500000）-1X5
=555550-5
=555545
two
（1+11+21+31+41）＋（9+19+29+39+49）
=(1+49)+(11+39)+(21+29)+(31+19)+(41+9)
=50X5
=250
three
.（9999+9997+9995+…… +9001）－（1+3+5+…… +999 ）
=(9999-999)+(9997-997)+(9995-995)+.+(9001-1)
=9000X999
=9000X(1000-1)
=8991000
four
111+789+12+222+678+12+333+567+12+456
=900+900+900+456+36
=2700+500-8
=3192
five
1400÷25÷8+350÷4÷125+69÷13+13÷9+11÷13+14÷9+6÷13
=（1400÷200）+（350÷500）+（69+11+6）÷13+(13+14)÷9
=7+0.7+86÷13+27÷9
=16.7+8÷13
=17.315
six
.（0.36×5.1×81）÷（0.17×8.1×0.4）
=（0.36÷0.4）×（5.1÷0.17）×（81÷8.1）
=0.9×30×10
=270

To solve five integral calculation problems in the second grade of junior high school and five calculation problems of binary linear equations

(X-6) (square of X + X + 1) - x (2x + 1) (3x-1) (y + 2) (Y-2) - (Y-1) (y + 5) (2a-b) (2a + b) - (3a-2b) (3a + 2b) (2x + Y-Z + 10) (2x-y + Z + 10) 11x2 + 4x-1-x2-4x-5 equation: 1) 66x + 17Y = 3967 25X + y = 1200 answer: x = 48 y = 47 (2) 18x + 23y = 2303 74x-y = 1998

The line L passing through point P (2,32) intersects with the positive half axis of X axis and the positive half axis of Y axis at points a, B and O respectively. The area of △ AOB is equal to 6

Let the equation of line l be XA + Yb = 1, then a (a, 0), B (0, b), and a ＞ 0, B ＞ 0. The area of ∵ AOB is equal to 6, ∵ 12ab = 6, ab = 12. ∵ point P (2, 32) is on line L, ∵ 2A + 32B = 1,