Respuesta:
a) 9a + 18 = 9
9a = 9 - 18
a = -9/9
a = -1
b) 8z - 24 = 24
8z = 24 + 24
x = 48/8
x = 6
c) 6b + 30 = 18
6b = 18 -30
b = -12/6
b = -2
d) 4x + 20 = 36
4x = 36 - 12
x = 24/4
x = 6
e) 24 - 4x = 20
4x = 24 - 20
x = 4/4
x = 1
f) 6a + 30 = 42
6a = 42 - 30
a = 12/6
a = 2