Question

Three friends bought 4, 6, and 8 books. The 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

Answer: B 7.5

Explanation:

Y = Kx

4 = k30

k = 30/4

k = 7.5

or

Y = KX

X Y