5<x<8
-3*5>-3x>-3*8
-24<-3x<-15
-24+3<-3x+3<-15+3
-21<=-3x+3<-12
а) 7(а³)²=7а⁶
б) (2³×5²×b³)² = (8×25×b³)² = (200×b³)² = 200²×b⁶ = 40000b⁶
в) (10²)³×c×(9d) = 10⁶×c×9d = 9000000cd
г) 6x²×7x³ = 42x⁵