Question

What are 2 ways of solving this proportion? 4/5 = 28/x

Answer 1

The first way is to cross multiply

4/5 = 28/x

4x = 5*28

4x = 140

4x/4 = 140/4

x = 35 which is the answer

=============================================

The second method is to note the denominators 4 and 28, and to ask yourself "what times 4 gets me 28?". The answer being 7, so 7*4 = 28. If you multiply top and bottom of the fraction 4/5 by 7, then you end up with 7*4 = 28 up top and 7*5 = 35 down below. This is another way of seeing how 4/5 = 28/35

Either way, the answer is x = 35