z : 3 = 7
12 + x =25
-40 + z = -10
3z=24
2x=24
x - 5 = 25
x - 4 = 37
4z=40
x : 2=13
-30+ z =70
z = 100
z=30
z=10
x=30
z=8
x=41
x=12
x=26
X=13
z=21