solve by substution

4x-3y=36
x=2y+7 solution

(1) 4x -3y = 36

(2) x - 2y = 7 mpy last eq. by 4:
(3) 4x - 8y = 28 subtract #3 from #1
(4) 5y = 8
y = 8/5 = 1 3/5
x = 7 + 2y = 10 1/5