Karan and Arjun work for 12 days then Aman and Ankur replaced them and complete the remaining work in 5 days. The efficiency of Karan and Arjun is in the ratio 4 : 3. Aman alone can complete work in 10 days and Ankur alone completes the work in 20 days. Find the number of days in which Karan and Arjun both complete the work.
1
48 days
2
24 days
3
42 days
4
21 days
5
30 days