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 30 applicants for a job, 9 had at least 4 years ' experience, 18 had degrees, and 3 had less than 4 years ' experience and did not have a degree. how many of the applicants had at least 4 years ' experience and a degree ?
Options: a. 14, b. 10, c. 9, d. 7, e. 5
[A]: b

[Q]: Problem: a can do a piece of work in 4 hours; b and c together can do it in 3 hours, while a and c together can do it 2 hours. how long will b alone take to do it ?
Options: a. 8 hours, b. 10 hours, c. 12 hours, d. 24 hours, e. none of these
[A]: c

[Q]: Problem: a lent rs. 5000 to b for 2 years and rs. 3000 to c for 4 years on simple interest at the same rate of interest and received rs. 1540 in all from both of them as interest. the rate of interest per annum is ?
Options: a. 7 %, b. 12 %, c. 74 %, d. 10 %, e. 45 %
[A]:
a