If x = 3 is the solution of equation 1 / 3x-b = 7, then B=

If x = 3 is the solution of equation 1 / 3x-b = 7, then B=

b=
1 / 3 * 3-B = 7
1—b=7
b=1—7
b=—6
This is my conclusion after meditation,
If not, please ask, I will try my best to help you solve it~
If you are not satisfied, please understand~

The results are as follows: X / 2-y / 5 = 4; X / 7-y / 15 = 3

X / 2-y / 5 = 4 ------ (1) x / 7-y / 15 = 3 ------ (2) x 3 - ①, we get: - X / 14 = 5, x = - 70, substituting x = - 70 into (2), we get: - 70 / 7-y / 15 = 3 - 10-y / 15 = 3, Y / 15 = - 13, y = - 195

To solve the equations {x + y 15 + X-Y 2 = 5, x + y 10-x-y 4 = - 2, use the method of assumption

Let 1 / (x + y) = M 1 / (X-Y) = n, then the original equations become:
15m+2n=5…… ① 10m-4n=-2…… ②
① X 2: 30m + 4N = 10 ③
② The solution is: M = 1 / 5
The solution is n = 1
∴x+y=5 x-y=1
Two equations are added to get: 2x = 6, solution: x = 3
Two equations subtraction: 2Y = 4, solution: y = 2