Answer : 1. "25"
Explanation :

Answer: A) 25 Explanation: (A+B+C) do 1 work in 10 days. So (A+B+C)'s 1 day work=1/10 and as they work together for 4 days so workdone by them in 4 days=4/10=2/5 Remaining work=1-2/5=3/5   (B+C) take 10 more days to complete 3/5 work. So( B+C)'s 1 day work=3/50 Now A'S 1 day work=(A+B+C)'s 1 day work - (B+C)'s 1 day work=1/10-3/50=1/25 A does 1/25 work in in 1 day Therefore 1 work in 25 days.