Indian milk market contains two types of products cow’s milk and buffalo’s milk. Commercial milk should have 80% milk. The cost of commercial milk of cow and buffalo cost Rs. 20 and Rs. 15 per liter respectively. At market both can be sold at 60% profit. A milkman who sells 70% milk as 80% and also mixes cow and buffalo in the ratio 3 ∶ 4 and sells it as cow milk. What is the profit (%) he earns?