A candy shop owner buys three kinds of candies: red, blue, and green. Red candies are purchased at 3 for ₹15, blue candies at 4 for ₹18, and green candies at 5 for ₹22. He mixes them in the ratio 1: 1: 2. He sells all the mixed candies at 2 for ₹10. What is his approximate gain or loss percentage?