2b+(7a-9b)=2b+7a-9b = 7a-7b = 7*(a-b)
-4x-(8p-4x) = -4x-8p+4x = -8p
(5+a)+(7a-5) = 5+a+7a-5 = 8a
-(4-8b)+(-8b-15) = -4+8b-8b-15 = -19
2b+(7a-9b)=2b+7a-9b = 7a-7b = 7*(a-b)
-4x-(8p-4x) = -4x-8p+4x = -8p
(5+a)+(7a-5) = 5+a+7a-5 = 8a
-(4-8b)+(-8b-15) = -4+8b-8b-15 = -19