# Thread: Ratio between 2 variables

1. ## Ratio between 2 variables

2/7 of one number is equal to 3/7 of second number. By how much percent should we decrease bigger number in order to make it equal to smaller number?

There are some questions like this and I want know how to solve them.

P.S. I'm not native English speaker and I could translated it little bit non grammatically.

2. ## Re: Ratio between 2 variables

$\dfrac 2 7 x = \dfrac 3 7 y$

$y = \dfrac 2 3 x$

$\text{assume }x,y>0 \text{ so }x>y$

$\text{We want to decrease }x \text{ by some percentage so that it equals }\dfrac 2 3 x$

$(100\% - p\%)x = \dfrac 2 3 x = 67.\bar{6}\% x$

$100\% - p\% = 66.\bar{6}\%$

$p = 33.\bar{3}\%$

They rounded it to get 33%