simplify :
12+-5x+6x=4
combine like terms :
-5x+6x=1x
12+1x=4
solving :
12+1x=4
solving for variable ‘x’
move all terms containing x to the left, all other terms to the right, add ‘-12’ to each side of the equation
12+-12+1x=4+-12
combine like terms:
then divide each side
your answer : x=-8
