a) `(120^3 )/( 4^3) = (120/4)^3=30^3=27000`
b) `(390^4)/(120^4)=(13/4)^4`
c) `(8^13)/(4^10) = (8/4)^10 . 8^3 = 2^10 . 2^9 = 2^19`
d) `820^50 +420/(4^25) + 64^5`
`= 2^50 . 5^100 . 17^50 + (2^2 . 105)/(2^50) + 2^11`
`= 2^11 (2^39 .5^100 . 17^50) + 105/(2^48)`