Question

A man purchased some eggs at 3 for Rs 5 and sold them at 5 for Rs 12. Thus, he gained Rs 143 in all. How many eggs did he purchase?

Answer 1

$$\begin{gathered} \mathrm{Let}x\mathrm{be}\mathrm{number}\mathrm{of}\mathrm{eggs}\mathrm{he}\mathrm{purchased}. \\ \mathrm{CP}\mathrm{of}3\mathrm{eggs}=\mathrm{Rs}.5 \\ \mathrm{CP}\mathrm{of}\mathrm{x}\mathrm{eggs}=\mathrm{Rs}.\frac{5}{3}x \\ \mathrm{SP}\mathrm{of}5\mathrm{eggs}=12 \\ \mathrm{SP}\mathrm{of}\mathrm{x}\mathrm{eggs}=\frac{12}{5}x \\ \therefore \mathrm{Gain}=\mathrm{SP}-\mathrm{CP} \\ =\frac{12}{5}x-\frac{5}{3}x \\ =\mathrm{Rs}.\frac{11}{15}x \\ \mathrm{Now},\frac{11}{15}x=143 \\ \Rightarrow x=143÷\frac{11}{15} \\ \Rightarrow \mathrm{x}=143\times \frac{15}{11}\Rightarrow \mathrm{x}=195 \end{gathered}$$