Question Number 211143 by boblosh last updated on 29/Aug/24
Answered by A5T last updated on 29/Aug/24
$${Let}\:{width}\:{be}\:{w}\Rightarrow{w}={y}+\mathrm{12} \\ $$$${perimeter}=\mathrm{2}\left({w}+{y}\right) \\ $$$$\mathrm{2}\left({w}+\mathrm{30}+{y}+\mathrm{30}\right)=\mathrm{3}×\mathrm{2}\left({w}+{y}\right) \\ $$$$\Rightarrow{w}+{y}=\mathrm{30}\Rightarrow{y}+\mathrm{12}+{y}=\mathrm{30}\Rightarrow{y}=\mathrm{9} \\ $$$$\Rightarrow{length}=\mathrm{9}\:{and}\:{width}=\mathrm{21} \\ $$