A shopkeeper buys two types of rice at the rate of Rs. 35/kg and Rs. 28/kg respectively. If he sells this mixture for Rs. 36/kg, he makes a profit of 20%. What is the ratio of the mixture in which both the rice are mixed?
1
2 ∶ 5
2
4 ∶ 7
3
7 ∶ 4
4
5 ∶ 3