Quantative Reasoning: p^2+q^2=25, 2pq=10, find (p-q)^2

[foood]

if p²+q²= 25 and 2pq=10, what is (p-q)²?

a)250
b)100
c)50
d) 5

i dont get this...the answer is b) and i guessed c).
i only know that pq=5 and possible values for the p and q in p²+q²= 25 are p=4 and q=3 or vice versa.

[theshadow]

i'm surprised nobody answered this. you need to use the perfect squares formula: (p-q)^2 = p^2-2pq+q^2

then p^2+q^2-2pq = 25-10 = 15 = (p-q)^2

i think all the answers are wrong