Question

What is the best way to begin solving the following system by substitution?

-7x - 2y = -13
x - 2y = 11

Answer 1

Solve for variable y in the first of second equation.

Lets do the second

x-2y=11
-2y = 11-x
y = (11-x)/-2
y = -11/2 + x/2
y = 1/2x - 11/2

Substitute into first equation
-7x-2(1/2x-11/2)=-13
-7x -x +11 = -13
-8x = -13 -11
-8x = -24
x=3

Which you can substitute into the second eqn

(3)-2y=11
-2y = 11-3
-2y = 8
y=-4