Question

5x+12=-7x solve each system by subsitution

Answer 1

on the problem minus 5x to the -7 so you'll just have 12= -12x and the answer is x=-1 

Answer 2

5x+12=-7x
12x+12=0 (+7x)
12x=-12 (-12)
x=-1 (/12)

y=5x+12
y=5(-1)+12
y=-5+12
y=7

Hope this helps:)