Question

A discount of 16% on the marked price of a book enables a man to buy a pen which costs Rs 80. How much did he pay for the book?

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{MP}\mathrm{of}\mathrm{the}\mathrm{book}=\mathrm{Rs}x \\ \mathrm{Rate}\mathrm{of}\mathrm{discount}=16\% \\ \mathrm{Discount}=16\%\mathrm{of}\mathrm{Rs}x=\mathrm{Rs}\left(\frac{16x}{100}\right)=\mathrm{Rs}\left(\frac{4x}{25}\right) \\ \mathrm{Now},16\%\mathrm{discount}\mathrm{on}\mathrm{MP}\mathrm{of}\mathrm{book}\mathrm{enables}\mathrm{a}\mathrm{man}\mathrm{to}\mathrm{buy}\mathrm{a}\mathrm{pen}\mathrm{of}\mathrm{Rs}80. \\ \mathrm{So},\mathrm{according}\mathrm{to}\mathrm{question}, \\ \frac{4x}{25}=80 \\ \Rightarrow x=500 \\ \mathrm{Now},\mathrm{Marked}\mathrm{price}\mathrm{of}\mathrm{the}\mathrm{book}=\mathrm{Rs}500 \\ \mathrm{Selling}\mathrm{price}\mathrm{of}\mathrm{the}\mathrm{book}=\mathrm{MP}-\mathrm{discount}=500-80=\mathrm{Rs}420 \\ \mathrm{So},\mathrm{the}\mathrm{man}\mathrm{buys}\mathrm{the}\mathrm{book}\mathrm{for}\mathrm{Rs}420. \end{gathered}$$