### A man sold two chairs at Rs. 1200 each. On one he gained 20% and on the other he loss 20%. His gain or loss in the whole transaction is:

A. 1% loss B. 2% loss C. 4% loss D. 15 gain Answer: Option C
In the case where loss and gain percentage is common on same selling price, always a loss incurs in total deal. And this can be calculated by a short-cut: Loss on total deal, $\begin{array}{l}=\left(\Large\frac{\text{ Common loss or gain percentage }}{10}\right)^2\\ =\left(\Large\frac{20}{10}\right)^2\\ =4\%\end{array}$ Alternatively It can be also calculated through Graphic Change Method: This can be given by, 100 == 20% gain ⇒ 120 == 20% loss ⇒ 96 Loss = 4% (As 100 became 96)