Hi, in my math textbook I have three question which the textbook does not teach you how to simplify please help. I don't just want the answer I want to know how to get the answer again if I receive a similar question.

These are the three questions. The correct answers are below each question question

Simplify...

131. (2^(n+2) + 12) / (5 * 2^n + 15)

4/5

132. (2^(2n+3) - (2n)^2) / 2^n

7 * (2^n)

133. (3^(n+1) + 9) / (3^(n-1) + 1)

9

Thanks in advance