Tolong di hawab please

(7-5m) + (-8+15m)
= 7-8 -5m + 15m
= -1 +10m

(10-6m)-(-8+15m)
= -6m - 15m +10 + 8
= -21m + 18

(-1 + 10m) + (18-21m)
= -1 + 18 + 10m -21m
= 17 + (-11)