Add:
3p2q 2 – 4pq + 5, – 10 p2q 2 , 15 + 9pq + 7p2q 2

Dear Student

When term have the same algebraic factors, they are like terms. Then, we have to add the like terms
= 3p^2q^2–4pq + 5 + (- 10p^2q^2) + 15 + 9pq + 7p^2q^2
= 3p^2q^2–10p^2q^2+ 7p^2q^2–4pq + 9pq + 5 + 15
= p^2q^2(3 -10 + 7) + pq (-4 + 9) + (5 + 15)
= p^2q^2(0) + pq (5) + 20
= 5pq + 20

Thanks