Write out the equation
12-4x=3+x
Solve for x by passing all x terms to the left and all non x terms to the right
-4x-x=3-12
-5x=-9
Divide both sides by -5 to isolate x
x=-9/-5
Do the divison in the calculator and get:
x=1.8
Or leave it in fraction form (signs go positive since both were negative)
x=9/5
