Reena goes to a shop to buy a radio costing Rs. 2568. The rate of sales tax is 7% and the final value is rounded off to the next higher integer. She tells the shopkeeper to reduce the price of the radio so that she has to pay Rs. 2568 inclusive of sales tax. Find the reduction needed in the price of the radio.

Let initial price 100 unit then final price will be 107 unit.
According to question
100units =2568
1 unit = 2568/100
7 units = (2568/100)×7=180

How can 180 be answer? For 2568 rs 7% service tax is 180rs (approx). If he directly gives 180 rs as a discount, then that is the discount he gave on whole price (including tax) but she asks him to reduce price of radio so that she pays 2568 including 7% tax. If she simple asks to give her a discount of certain amount then 180rs is the answer but she asks to reduce price of radio so 168rs reduction + 7% tax on reduced price amounts to 2568 rs.

Why not 180 ans?