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.

[EX Q]: Problem: a worker earns $ 20 on the first day and spends $ 15 on the second day. the worker earns $ 20 on the third day and spends $ 15 on the fourth day. if this pattern continues, on which day will the worker first reach a net total of $ 80 ?
Options: a. 24, b. 25, c. 27, d. 30, e. 32
[EX A]: b

[EX Q]: Problem: at the wholesale store you can buy an 8 - pack of hot dogs for $ 1.55, a 20 - pack for $ 3.05, and a 250 - pack for $ 22.95. what is the greatest number of hot dogs you can buy at this store with $ 205 ?
Options: a. 1,108, b. 2,100, c. 2,140, d. 2,124, e. 2,256
[EX A]: c

[EX Q]: Problem: i sold a book at a profit of 10 %. had i sold it for $ 110 more, 15 % would have been gained. find the cost price ?
Options: a. $ 2000, b. $ 2200, c. $ 3000, d. $ 3120, e. $ 1540
[EX A]:
b