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: if a / b = 4 / 3, then ( 3 a + 2 b. / ( 3 a - 2 b. = ?
Options: a. 6, b. 3, c. 5, d. - 1, e. none
b

Problem: if a certain coin is flipped, the probability that the coin will land heads is 1 / 2. if the coin is flipped 6 times, what is the probability that it will land heads up on the first 4 flips but not on the last 2 flips ?
Options: a. 1 / 8, b. 1 / 16, c. 1 / 32, d. 1 / 64, e. 1 / 128
d

Problem: one hour before john started walking from p to q, a distance of 33 miles, ann had started walking along the same road from q to p. ann walked at a constant speed of 3 miles per hour and john at 2 miles per hour. how many miles had ann walked when they met ?
Options: a. 6 miles, b. 8,4 miles, c. 9 miles, d. 9,6 miles, e. 21 miles
e