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

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Answer 1 · 2015-06-07T23:24:05

(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 -> $x = -1 -> y = 5 - 2 = 3.$

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

How do you solve by substitution 3x-4y=-153x-4y=-15 and 5x+y=-2 5x+y=-2?