A merchant buys 20 kgs. of a variety of rice at Rs. 14 per kg and another 40 kgs. of rice at Rs. 10. per kg. He mixes them and sells 13 of the mixture at Rs. 12.50 per kg. At what rate should he sell the remaining mixture so as to earn a profit of 25% on the whole outlay?
A.1. Rs.12.50
B.2. Rs.12
C.3. Rs.15
D.4. Rs.13