Question

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.

The system of equations shown can be used to find the number of multiple-choice questions, m, and the number of free-response questions, f, on the test.

m + f = 15

3m + 5f = 51

How many multiple-choice questions are on the test?

3
5
12
14

Answer 1

So the correct answer is 12.?

Explanation:

Answer 2

The right answer for the question that is being asked and shown above is that:

m + f = 15 ---> 3m + 3f = 45
3m + 5f = 51

3m + 3f = 45
3m + 5f = 51
-------------------
-2f = -6
f = 3

m + f = 15
m = 15 - 3
m = 12

So the correct answer is 12.