56-(x+12)=2456-x-12=24-x=24+12-56-x=-20x=20
55-(x-15)=3055-x+15=30-x=30-15-55-x=-40x=40
(x+15)-8=17-x-15-8=17-x=17+15+8-x=40x=-40
(24+x)-21=10-24-x-21=10-x=10+24+21-x=55x=-55
(45-y)+18=5845-y+18=58
-y=-5y=5