PLZ HELP!! What is the difference between unit rates and rates are different.

The heaviest 16% of all men in weight weigh more than how many pounds ?

Abiologist is recording the loss of fish in a pond. he notes the number of fish, f, in the pond on june 1. on july 1 there were 63 fish in the pond, which is 52 fewer fish than were in the pond on june 1. which equation represents this situation? a. f – 52 = 63 b. f – 63 = 52 c. 63 – f = 52 d. f – 63 = –52

Ineed to know the answer to this algebra question.