It should give you the option to do so.
1. Distribute
1/125 x 5n - 1/125
2. Simplify 1/125 x 5n to n/25
n/25 - 1/125
First step: Find out the prime numbers that make up the radical, for example, 120 would be 2x2x2x5x3
Second step: If there is 2 of the same number that repeats just put that number in the front of the resulting radical
Third: Just multiply the remaining radicals together and put the number in front of it.
Now you have