MR. Asif can do a job in 10 days. after working 3 days, he hires a helper and two completed the job in another 5 days. How long would it take have taken the helper to complete the task alone?
Asif works for 3 days.... now the job has 7 days remaining for Asif alone
1/7 + 1/x = 1/5
solve for x = 17.5 days for the slow assistant to finish the remaining job without Asif