Solve 67x – 5 = 12x + 13

First of all, we put all the unknowns to the same side. 67x and 12x will be on the left hand side; 13 and -5 are on the right hand side. For the unknowns, when 12x moves from right hand side to the left hand side its sign has changed becoming -12x; same case for -5, when it moves to the right hand side it becomes 5. Therefore, 67x-12x=13+5; then 55x=18; x=18/55