Question

Solve by substitution
3x y=-9
x-2y=-10

Answer 1

: 3x + y = 9
y = 9 - 3x

x - 2y = 10
y = (x - 10)/2

2(9 - 3x) = x - 10
18 - 6x = x - 10
7x = 28
x = 4

y = 9 - 3(4)
y = 9 - 12
y = - 3

Answer: x = 4, y = - 3

Proof—2nd equation:
4 - 2(- 3) = 10
4 + 6 = 10

Hope this helps :)