[tex]\it\ell=\dfrac{3}{4}L \ \ \ \ \ \ (1)\\ \\ \\ \mathcal{P}=2(L+\ell)=98\bigg|_{:2} \Rightarrow L+\ell=49 \Rightarrow \ell=49-L\ \ \ \ \ \ (2)\\ \\ \\ (1),\ (2) \Rightarrow \dfrac{3}{4}L=49-L\bigg|_{\cdot4} \Rightarrow 3L=4\cdot49-4L\bigg|_{+4L} \Rightarrow 7L=4\cdot49\bigg|_{:7} \Rightarrow \\ \\ \\ \Rightarrow L=4\cdot7 \Rightarrow L=28\ m\\ \\ \\ (2),\ (3) \Rightarrow \ell=49-28[/tex]
