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: 6 men and 8 women can complete a work in 10 days. 26 men and 48 women can finish the same work in 2 days. 15 men and 20 women can do the same work in - days.
Options: a. 4 days, b. 6 days, c. 2 days, d. 8 days, e. 10 days

A: a
****
Q: Problem: a solution of 70 litres contains oil and water in the ratio 9: x. if 6 litres of water is added to the solution, the ratio becomes 6: 4, find the value of x ?
Options: a. 6, b. 8.5, c. 9, d. 6.5, e. 5

A: e
****
Q: Problem: tanks a and b are each in the shape of a right circular cylinder. the interior of tank a has a height of 10 meters and a circumference of 9 meters, and the interior of tank b has a height of 9 meters and a circumference of 10 meters. the capacity of tank a is what percent of the capacity of tank b ?
Options: a. 75 %, b. 90 %, c. 100 %, d. 120 %, e. 125 %

A:
b
****