Unit rate is a rate with 1 in the denominator.
First of all, you have to figure out how much water a person should drink per 1 minute:
32 ÷ 60 = 0.53
(Unit rate will be 0.53/1)
Secondly, multiply 0.53 by 135:
0.53 x 135 = 72
Answer: Damon should drink 72 fluid ounces of water if he rides his bike for 135 minutes.