45x = 180
divide by 45
x=4
yes
420 /d = 30
multiply by d
420 =30d
divide by 30
14 =d
no d=14
37+s = 80/2
37+s =40
subtract 37 from each side
s =3
no s=3
52+g =45+11
52+g = 56
subtract 52 from each side
g=4
no g=4
13+14 = 3f
27 = 3f
divide by 3
9=f
yes f=9