Answer
$(b-6)(b-9)$
Work Step by Step
The first term in each binomial must be b, since $b^2$ has no coefficient.
The operation in each binomial must be subtraction, since the trinomial has a positive and a negative term.
$-6+(-9)=-15$ and $-6\times(-9)=54$, so the other two terms are -6 and -9.
