Make sure every factor, whether it's a number or a letter, 
in the numerator and the denominator shows its exponent even 
if its exponent is 1 understood:



To remove the parentheses, multiply every exponent inside
the parentheses by the 4 exponent outside the parentheses:





Use the rule for subtracting exponents:

If a factor of the numerator has the same base as a
factor of the denominator, then 

1. If the exponent in the NUMERATOR is larger than the
   exponent in the DENOMINATOR, then subtract the exponents
   (larger minus smaller) and place the result as an exponent
   of the base in the NUMERATOR.

2. If the exponent in the DENOMINATOR is larger than the
   exponent in the NUMERATOR, then subtract the exponents
   (larger minus smaller) and place the result as an exponent
   of the base in the DENOMINATOR. 

We see in



that the n in the denominator has a larger exponent than the
n in the numerator so we subtract 20-4, getting 16 and place
 in the denominator, since the larger exponent was
there:



We also see that the p in the denominator has a larger exponent 
than the p in the numerator so we subtract 8-4, getting 4 and place
 in the denominator, since the larger exponent was
there:



The only thing left to do is to replace the  by
 and the  by 



That's it!

Edwin