Vishal lives in town A. He leaves his house for exactly 10 hours everyday to sell fruits. He purchases his fruits from either local Town A market or from any of the three neighbouring towns B, C or D. It takes him 1 hour to reach C and 1.5 hour to reach D from A. The time required for traveling from B to C, C to D or B to D is 1 hour. In 1 hour, he sells, exactly 1 kg of fruits. The rates of fruits in the four towns are as follows: A = Rs. 20/kg, B = Rs. 25/kg, C = Rs. 10/kg, D = Rs. 11/kg. He completes each day without any stock at the end. Assume that the buying and selling price are the same.

How many extra hours should Vishal put in, in order to earn Rs. 120?