You need to bring all the variables to one side and the constants to the other side.
an example:-
12x + 5 = 3x + 32
add -3x to both sides
12x - 3x + 5 = 3x - 3x + 32
9x + 5 = 32
now add -5 to both sides
9x + 5 - 5 = 32 - 5
3x = 27
THe important point is to keep the equation in balance by performing the same operation on both sides of the '='.
Hope this helps