Question

cost of an article is rs x and is sold at a profit of (x+10).find the cost of price if its selling price is rs (2x-20)

Answer 1

Instead of profit of (x+10),it must be (x+10)%.

C.P= Rs x
S.P=Rs (2x-20)

$$\begin{gathered} \mathrm{Now}, \\ \mathrm{C}.\mathrm{P}+\mathrm{Profit}=\mathrm{S}.\mathrm{P} \\ \mathrm{i},\mathrm{e} \\ \mathrm{x}+(\mathrm{x}+10)\%\mathrm{of}\mathrm{x}=2\mathrm{x}-20 \\ \Rightarrow \mathrm{x}+\frac{(\mathrm{x}+10)\mathrm{x}}{100}=2\mathrm{x}-20 \\ \Rightarrow 100\mathrm{x}+{\mathrm{x}}^2+10\mathrm{x}=200\mathrm{x}-2000 \\ \Rightarrow {\mathrm{x}}^2-90\mathrm{x}+2000=0 \\ \mathrm{Solving}\mathrm{the}\mathrm{Q}.\mathrm{E}\mathrm{in}\mathrm{x}, \\ \mathrm{x}=\frac{-\mathrm{b}\pm \sqrt{{\mathrm{b}}^2-4\mathrm{ac}}}{2\mathrm{a}} \\ \mathrm{x}=\frac{90\pm \sqrt{{90}^2-4\times 1\times 2000}}{2\times 1} \\ \mathrm{x}=50,40 \end{gathered}$$