Question

If the area is $3xc{m}^2$, make an equation, and find $x$.

Answer 1

$\begin{array}{c}Area=3kc{m}^2\left(given\right)\\ weknowareaofrec\tan gle=\\ \Rightarrow 8\times \left(x-5\right)=3x\\ \Rightarrow 8x-4=3x\\ \Rightarrow 5x=40\\ \Rightarrow x=8cm\end{array}$