Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[Q]: Problem: for each of her sales, a saleswoman receives a commission equal to 20 percent of the first $ 500 of the total amount of the sale, plus 35 percent of the total amount in excess of $ 500. if the total amount of one of her sales was $ 800, the saleswoman ' s commission was approximately what percent of the total amount of the sale ?
Options: a. 22 %, b. 24 %, c. 25 %, d. 26 %, e. 28 %
[A]: d

[Q]: Problem: an engine moves at the speed of 30 kmph without any coaches attached to it. speed of the train reduces at the rate that varies directly as the square root of the number of coaches attached. when 9 coaches are attached speed decreases to 18 kmph. what will be the speed of train when 16 coaches are attached.
Options: a. 14, b. 16, c. 18, d. 20, e. 22
[A]: a

[Q]: Problem: in a certain pond, 50 fish were caught, tagged, and returned to the pond. a few days later, 50 fish were caught again, of which 5 were found to have been tagged. if the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, what is the approximate number of fish in the pond ?
Options: a. 400, b. 500, c. 1,250, d. 2,500, e. 10,000
[A]:
b