Let the marked price be Rs 100 ⇒ Discount =10%=1∕10=(10−1)∕10=9∕10 S.P=9∕10×100=90 Now, Discount percent in the first case =50% of 10 ⇒50∕100×10=5% And, Discount percent in the second case =40% of the first case ⇒40∕100×5=2% Now the selling price in season is, ⇒90×(100−5)∕100×(100−2)∕100 ⇒90×95∕100×98∕100 ⇒83.79 Hence the actual discount is, ⇒100−83.79=16.21 ∴ The percentage rate of the equivalent single discount 16.21%