for what values of p and q the following system of equations will have infinite solutions 2x+3y=7 and (p-q)x(2 p-q)y=21

Please note that there is a typing mistake in the second equation. It should be (p-q)x + (2 p-q)y=21 instead of (p-q)x(2 p-q)y=21. 

 

So, for infinite solutions

 

2/p-q = 3/2p-q = 7/21

 

Hence, p-q = 6

2p-q = 9

 

Solving simultaneously, p = 3

q = -3