Correct option (d) 7 days
Explanation:
A leave the work 5 days before completion and B after 2 days when A
leave. S Do C work alone for the last three days. C = 4×3=12 unit
Before it (B+C) work for 2 days = 9×2=18 unit
Remaining = (60-30) unit done by (A+B+C)
No. Of days taken by them (A+B+C)
30/15 (6 +5 +4 ) = 2 days
Total days = 3+2+2= 7 days.
