S, T and U can complete a work in 40, 48 and 60 days respectively. They received Rs 10800 to complete the work. They begin the work together but T left 2 days before the completion of the work and U left 5 days before the completion of the work. S has com

S, T and U can complete a work in 40, 48 and 60 days respectively. They received Rs 10800 to complete the work. They begin the work together but T left 2 days before the completion of the work and U left 5 days before the completion of the work. S has completed the remaining work alone. What is the share of S (in Rs) from total money?
1). 4000
2). 4320
3). 4500
4). 4860

4860 is the correct answer as per the ssc answer key

$ S \text{ can complete the work in } 40 \text{ days } \Rightarrow \text{One day work} = \frac{1}{40} $
$ T \text{ can complete the work in } 48 \text{ days } \Rightarrow \text{One day work} = \frac{1}{48} $
$ U \text{ can complete the work in } 60 \text{ days } \Rightarrow \text{One day work} = \frac{1}{60} $

$ \text{Let total work be } 240 \text{ (LCM of 40, 48, 60)} $

$ S \text{ efficiency} = \frac{240}{40} = 6 $
$ T \text{ efficiency} = \frac{240}{48} = 5 $
$ U \text{ efficiency} = \frac{240}{60} = 4 $

$ \text{Let total work be completed in } X \text{ days} $
$ \text{T worked for } (X-2) \text{ days, U worked for } (X-5) \text{ days} $

$ \text{Total work done:} $
$ 6X + 5(X-2) + 4(X-5) = 240 $

$ 6X + 5X - 10 + 4X - 20 = 240 $
$ 15X - 30 = 240 $
$ 15X = 270 $
$ X = 18 $

$ \text{Work done by S: } 6 \times 18 = 108 $
$ \text{Total payment } = 10800 $
$ \text{Share of S} = \frac{108}{240} \times 10800 = 4860 $

$ \text{Answer: } 4860 $