Kantilal mixes 80 kg of sugar worth of Rs. 6·75 per kg with 120 kg worth of Rs. 8 per kg. At what rate shall he sell the mixture to gain 20 %?

According to question ,
Total C. P. of 200 kg of mixture = Rs. (80 × 6·75 + 120 × 8)
Total C. P. of 200 kg of mixture = Rs. 1500
Average rate = Rs. 7·50 per kg
Required rate = 120% of Rs. 7·50
Required rate = Rs. 9 per kg.