Greeshma bought 10 kg of pasta at ₹50 per kg, x kg of pasta at ₹60 per kg and (x – 3) kg of pasta at ₹65 per kg. He mixed all types of pasta together and the average cost price of 1 kg of pasta was ₹57.20. What is the quantity (in kg) of pasta bought at the rate of ₹65 per kg?