# How do you solve by substitution 3x-4y=-15 and  5x+y=-2?

Jun 7, 2015

(1) 3x - 4y = - 15

(2) 5x + y = - 2 --> y = - 5x - 2. Substitute this value into (1):

3x - 4(-5x - 2) = - 15

3x + 20x + 8 = - 15

23x = -23 -> $x = - 1 \to y = 5 - 2 = 3.$

Check with equation (1): - 3 - 12 = - 15 . Correct.