Explanation:
15+12x=13x+5
we move all terms to the left :
15+12x-(13x+5)=0
We get rid of parentheses
12x-13x-5+15=0
We add all the numbers together , and all the variables
-1x+10=0
We move all terms containing x to the left , all other terms to the right
-x = -10
x = -10/-1
x= +10