`50)`
a) `(1/5)^{5}.5^5`
`=(1/(5).5)^5`
`=1^5`
`=1`
b) `(0,125)^{3}.512`
`=(1/8)^{3}.8^3`
`=(1/(8).8)^3`
`=1^3`
`=1`
c) `(0,25)^{4}.1024`
`=1/(256).1024`
`=4`
`51)`
a) `(120^3)/(40^3)=3^3=27`
b) `(390^4)/(130^4)=3^4=81`
c) `(3^2)/(0,375)^2=9 : 9/(64)=64`