Two types of milk, A and B, are mixed and then sold at Rs.60 per liter. The profit is 15% if A and B are mixed in the ratio 3 : 1, and 20% if this ratio is 1 : 3. The cost prices, per litre, of A and B are in the ratio
1
23 : 17
2
43 : 41
3
49 : 45
4
51 : 57