The variables x and y are related proportionally. When x = 4, y = 10. Find y when x = 20

Answer 1

Hi!

We first need to have clarity on what a "proportion" is... it's just simply a ratio.. so we can do x/y or even y/x to compare the ratios of the numbers..

lets just do x/y..

So, 4/10 = 2/5 simplified... So this ratio must be EQUAL to 20 divided by some number, which is y... So now we just solve for y.. you have to cross multiply in the following step:

2/5 = 20/y

100 = 2y

y=50...

We can check our answer by dividing 20/50 to see what the ratio is... as you can see, the 0's cancel out, and we are left with 2/5. Boom! Done! The answer is y=50!