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 circumference of the front wheel of a cart is 30 ft long and that of the back wheel is 32 ft long. what is the distance traveled by the cart, when the front wheel has done five more revolutions than the rear wheel ?
Options: a. 20 ft, b. 25 ft, c. 750 ft, d. 900 ft, e. 2400 ft
e

Problem: if two dice are thrown together, the probability of getting an even prime number on the dice is
Options: a. 1 / 36, b. 1 / 18, c. 1 / 13, d. 1 / 9, e. 5 / 36
a

Problem: at a certain restaurant, the average ( arithmetic mean ) number of customers served for the past x days was 65. if the restaurant serves 120 customers today, raising the average to 90 customers per day, what is the value of x ?
Options: a. 1, b. 5, c. 9, d. 15, e. 30
a