9x - y = 15
2x + 8y = 28
Use the substitution method.
Solve for y in the first equation.
9x - y = 15
-y = 15 - 9x
y = -15 + 9x
Now plug in y into the second equation.
2x + 8(-15 + 9x) = 28
2x - 120 + 72x = 28
74x - 120 = 28
74x = 148
x = 2
Plug x back into the rewritten first equation.
y = -15 + 9(2)
y = -15 + 18
y = 3
x = 2, y = 3