algabra

4q + 5 = 5
4q + 5 - 5 = 5 - 5
4q = 5
(4q)/4 = 5/4
q = 5/4 = 1.25

Guest:

4q + 5 = 5
4q + 5 - 5 = 5 - 5
4q = 5

but
4q + 5 - 5 = 5 - 5
is
4q = 0
so is
q=0

[input]4x+5=5[/input]