Question

Solve for y in the following system of equations:

x - y = -1
3x + 5y = 21

Answer 1

to Eliminate x

x - y = -1
3x + 5y = 21

multiply (x - y = -1) by -3
-3x + 3y = 3
3x + 5y = 21
add both equations
0 + 8y = 24
8y = 24
y = 3