Please help me solve this problem.

Students are given 3 minutes for each multiple-choice question and 5 minutes for each free-response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it.how many multiple-choice questions are on the test?

Evaluate-27 ^4/3/8 a) - 81/16 b) 81/16 c) 16/81

This question awards 100 ! i really don’t want to fail i will also mark you !