How to do a cross proportions

   1           3
    =  
   5           x

In a proportion, u cross multiply. Take the denominator of the first fraction and multiply it by the numerator of the second fraction. Then take the numerator of the first fraction and multiply it by the denominator of the second fraction.

(5)(3) = (1)(x) ...now multiply
15 = x

and u will see from the answer   1/5 = 3/15 that these are equivalent fractions because that is all proportions are..they are just equivalent fractions.

Here is another one...
2/11 = x/22 cross multiply
(11)(x) = (22)(2)
11x = 44
x = 44/11
x = 4

2/11 = 4/22equivalent fractions