Question

What value of x makes this proportion true?

3/x=15/40
O A. 5
O B. 105
O C. 8
O D. 28

Answer 1

I believe that c would be the answer ;)

Answer 2

The answer would be C. 8.
I would cross multiple the fractions (3*40) and (15 * x)
That would equal 15x= 120
Divide both sides by 15 and you get 8
Or
You could say: what number times 3 gives me 15? The answer would be 5 and then you would divide 40 by 5 to get 8.

Hope the explanation helps :)