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: of the diplomats who attended a summit conference: 20 spoke japanese, 32 did not speak russian and 20 % of the diplomats spoke neither japanese nor russian. if 10 % of the diplomats spoke both japanese and russian, then how many diplomats attended the conference ?
Options: a. 70, b. 96, c. 108, d. 120, e. 150
[A]: d

[Q]: 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
[A]: c

[Q]: Problem: if the price of a certain bond on may 1 st was 3 / 4 the price of the bond on june 1 st and the price of the bond on july 1 st was 25 % greater than the price of the bond on may 1 st. then the price of the bond on june 1 st st was what percent of the average ( arithmetic mean ) price of the bond on may 1 st and july 1 st ?
Options: a. 50 %, b. 75 %, c. 118.5 %, d. 133 1 / 3 %, e. 150 %
[A]:
c