SAT Linear functions Question

$\mathrm{f}(\mathrm{x})=2x+3$ $g(x)=7x-2$ $\mathrm{h}(\mathrm{x})=5x+6$ The functionsf,g,and h are defined as shown. If $f(x)\cdot g(x)-h(x)=a{x}^2+bx+C$ , where a,b,and c are constants,what is the value ofb?