first u would take the 18 and - it on both sides
18 - 18 - 4x = -2 - 18
which would be
-4x = -20
then u would divide 4 on bothe sides
-4x/4 = -20/4
which would give u
- x = - 5
this is the answer for the negative x
for positive u would flip the answer
so
x = 5 which then = 4
x=5 is ur answer
hope this helps or u understand wat im sayin