Tip: When writing math questions, the coefficient would go in front of variables: 7b*

Anyways, in this case, since we cannot mutiply 7 by b, the 7 will stay put
But.... we can mutiply b by b

=b^3
Tip: B's with no exponent has an exponent with one
Questions?
So,7 will stay put and b and b^2 will simply to b^3
=Answer