You've got all the basic information, but you need to work to get it to be useful. What was the total cost? He bought 125 kg at Rs 25 per kilogram, so multiply the amount (125) by the cost per kg. (25) to get the total cost.
Next we have to see how much he has to sell. Since 5 kg were bad, he has only 120 to sell. He wants to make 20% profit, so that is 20% more than the total cost. Multiply the total cost by 20% (.2) to get the profit, and add that to the total cost to get amount he wants to make. He wants to make that on the 120 kg. he has left to sell, so divide the amount he wants to make by the 120 kg. and that will tell you how much he has to charge per kg. to make his 20% profit.
Keep working!
Mary
