Question

One ball pen costs ₹x and one fountain pen costs ₹y. Find the cost of y² ball pens and x² fountain pens.

Answer 1

$$\begin{gathered} \mathrm{As},\mathrm{the}\mathrm{cost}\mathrm{of}\mathrm{one}\mathrm{ball}\mathrm{pens}=₹x \\ \mathrm{So},\mathrm{the}\mathrm{cost}\mathrm{of}{y}^2\mathrm{ball}\mathrm{pens}=x\times y^2=₹x{y}^2 \\ \mathrm{Also},\mathrm{the}\mathrm{cost}\mathrm{of}\mathrm{one}\mathrm{fountain}\mathrm{pen}=₹y \\ \mathrm{So},\mathrm{the}\mathrm{cost}\mathrm{of}{x}^2\mathrm{fountain}\mathrm{pens}=y\times x^2=₹y{x}^2 \\ \mathrm{Now},\mathrm{the}\mathrm{total}\mathrm{cost}=₹\left(x{y}^2+y{x}^2\right) \end{gathered}$$