R alone can complete a piece of work in 10 days while R and S working together can complete it in 7 days. Find the ratio of efficiency of R and S.
1
5 ∶ 4
2
6 ∶ 5
3
7 ∶ 10
4
7 ∶ 3
R alone can complete a piece of work in 10 days while R and S working together can complete it in 7 days. Find the ratio of efficiency of R and S.