Can someone please explain how to solve this problem? The picture doesn't copy but the question can be found in the quantitative tutorial titled: The Many Ways the GMAT Tests Ratios. Please help!!

What is the value of p if if rq is not equal to 0?

(1) r = 4
(2) q = 3r

Thanks!!!

Could you please walk me through how you simplified the expression? I am having trouble understanding how you got p=(6/7)*(q/r).

Thanks!