1) 12 - y = 15
-y = 15 - 12 Additive Inverse
-1(-y = 3 ) -1 Multiplicative Inverse
y = -3
23.) 7 = 3 + z
7 - 3 = z Additive Inverse
z = 4
24) z - 12 = 8
z = 8 + 12 Additive Inverse
z = 20
25) 11 = 4 - w
11 - 4 = -w Additive Inverse
-1(7 = -w )-1 Multiplicative Inverse
w = - 7
