72/80-(x-12/80) =15/80

x-12/80=72/80-15/80

x-12/80=57/80

x=57/80+12/80

x=69/80

x+7/50=3/50+27/50

x+7/50=30/50

x+7/50=30/50

x=30/50-7/50

x=23/50

116/125-(41/125+x) =24/125

41/125+x=116/125-24/125

41/125+x=92/125

x=92/125-41/125

x=51/125

4/40+y+16/40=31/40+6/40

4/40+y+16/40=37/40

y=37/40-(4/40+16/40)

y=37/40-20/40

y=17/40