Question

Three friends bought 4, 6, and 8 books.

This table shows the cost of the books.
Number of Books 4 6 8
Cost ($) 30 45 60

What is the constant of proportionality?

A. 2
B. 7.5
C. 15
D. 30

Answer 1

B. 7.5

Explanation:

I just took the test on k-12 and it was correct.

Answer 2

B:7.5

Explanation:

since 4 goes with 30, 6 goes with 45, and 8 goes with 60, you can see that 60-45 is 15 and 45-30 is 15 as well so the constant is 15, but the number of books is going up by two so the constant there is 2. So divide 15 by 2 and the answer would be C: 7.5.