 Hello and welcome to the session. In this session we are going to discuss the following question and the question says that a trader buys goods at 18% off on list price. He wants to get a profit of 20% after allowing a discount of 10%. At what percent above list price should he mark the goods? Before we start we shall review some of the formulas. We know profit is equal to selling price minus cost price. Also profit percent is equal to profit upon cost price into 100. This implies cost price into profit percent is equal to profit into 100. Now as profit is equal to selling price minus cost price, therefore this implies cost price into profit percent is equal to selling price minus cost price into 100 which implies selling price is equal to cost price into profit percent plus cost price into 100 upon 100 is equal to cost price into 100 plus profit percent upon 100. Also selling price is equal to 100 minus discount percent upon 100 into mark price. With this key idea we shall proceed with the solution. Let the list price be 100 dollars. The mark price be x percent more than the list price. List price is equal to 100 dollars. Mark price is equal to 100 plus x dollars. Now as the trader buys goods at 18% off on list price this implies cost price is equal to 100 minus 18% off 100 dollars which is equal to 100 minus 18 dollars that is equal to 82 dollars. Now as profit is equal to 20% selling price is equal to cost price into 100 plus profit percent upon 100. This implies selling price is equal to 100 plus 20 upon 100 into 82 dollars that is equal to 120 upon 100 into 82 dollars that is 492 upon 5 dollars. Now as mark price is equal to 100 plus x dollars and discount is equal to 10% we know selling price is equal to 100 minus discount percent upon 100 into mark price. This implies selling price is equal to 100 minus 10 upon 100 into 100 plus x dollars which is equal to 90 upon 100 into 100 plus x dollars which is equal to 9 into 100 plus x upon 10 dollars. Now as we calculated the selling price was 492 upon 5 dollars and here it is 9 into 100 plus x upon 10 dollars therefore 492 upon 5 is equal to 9 into 100 plus x upon 10 this implies 492 into 2 is equal to 9 into 100 plus x which implies 492 into 2 upon 9 is equal to 100 plus x that is 328 upon 3 is equal to 100 plus x which implies 109.33 is equal to 100 plus x that implies x is equal to 109.33 minus 100 which is equal to 9.33. Hence x is equal to 9.33% which is our answer. This completes our session. Hope you enjoyed the session.