How to know wether to subtract or add? Looking for measure of angle 2 Angles:m∠1 = 10x + 2, and m∠2 = 12x – 22 Angles in Equation:10x+2=12x-22 Correct Like terms:2+22=12x-10x Why is it not 10x+12x=2-22 when the like terms are added together?