During month-long annual sale, a shopkeeper sells his goods at a discount of 50%. But in the last week, he offers an additional discount of 40%. If the original price of a shirt is Rs. x, then the price (in rupees) during the last week of the sale will be = ?

$$\eqalign{ & {\text{Single equivalent discount}} \cr & = \left( {50 + 40 - \frac{{50 \times 40}}{{100}}} \right)\% \cr & = 70\% \cr & \therefore {\text{Required price of shirt }} \cr & {\text{ = }}\left( {100 - 70} \right)\% {\text{ of }}x \cr & = 30\% {\text{ of }}x \cr} $$