Question

a. Length of a rectangle is three times its breadth. Perimeter of the rectangle is 40cm. Find its length and width.

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{width}\mathrm{of}\mathrm{the}\mathrm{rectangle}=\mathrm{x}\mathrm{cm} \\ \mathrm{Then}\mathrm{length}\mathrm{of}\mathrm{rectangle}=3\mathrm{x}\mathrm{cm} \\ \mathrm{Now},\mathrm{perimeter}=40\mathrm{cm} \\ \Rightarrow 2\left[\mathrm{length}+\mathrm{breadth}\right]=40 \\ \Rightarrow 3\mathrm{x}+\mathrm{x}=20 \\ \Rightarrow 4\mathrm{x}=20 \\ \Rightarrow \mathrm{x}=\frac{20}{4}=5 \\ \mathrm{So},\mathrm{width}=5\mathrm{cm} \\ \mathrm{length}=3\times 5=15\mathrm{cm} \end{gathered}$$