Three people P, Q, R can do a piece of work in 18 days, 24 days, and 30 days respectively. if P works regularly and (Q + R) help him every third day. how long will it take for them to complete the work?
1
12 days
2
\(12\frac12\) days
3
\(12\frac35\) days
4
13 days
5
\(13\frac23\) days