Think of this as a triangle. There is no way you could make p and q fit together if one of them is 2 or 3 and the other is given as 3. The most those two would be 6 which is less than 7.
8 would work. You'd get a triangle where 3 went up and 7 was horizontal. You could make 8 work.
13 is too big. Your answer must be less than 10
This is a tricky question. Thanks for posting.