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.

Problem: the total age of a and b is 16 years more than the total age of b and c. c is how many year younger than
Options: a. 14 years, b. 12 years, c. 56 years, d. 16 years, e. 55 years
d

Problem: a waitress ' s income consists of her salary and tips. during one week, her tips were 3 / 4 of her salary. what fraction of her income for the week came from tips ?
Options: a. 1 / 9, b. 1 / 6, c. 3 / 7, d. 4 / 9, e. 5 / 9
c

Problem: a garrison of 2000 men has provisions for 54 days. at the end of 18 days, a reinforcement arrives, and it is now found that the provisions will last only for 20 days more. what is the reinforcement ?
Options: a. 1977, b. 1600, c. 1979, d. 1900, e. 1278
b