Andrew M. answered 11/04/15
Tutor
New to Wyzant
Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors
The commutative property of multiplication says that
a x b = b x a
This is the property used showing
2 x 5 = 5 x 2 = 10
I don't see a missing number in your question.