[tex]\bf \textit{area of a triangle}\\\\ A=\cfrac{1}{2}bh~~ \begin{cases} b=base\\ h=height\\[-0.5em] \hrulefill\\ A=5\\ b=x\\ h=x-9 \end{cases}\implies 5=\cfrac{1}{2}(x)(x-9)[/tex]
