A carpenter worked alone for 1 day on a job that would take him 6 more days to finish. He and another carpenter completed the job in 5 more days. How many days would it have taken the second carpenter to do the complete job working alone?  Choose one:
A) 4.5	B) 7.5	C) 9.5	D) 17.5	E) 24.5

Rationale: a carpenter worked only 1 day on something that takes him 6 more days . means ; carpenter finishes his work in 7 days . let his buddy finish the same task in x days . respective rates per day : 1 / 7 and 1 / x to complete 1 work : first guy worked for 5 days @ rate = 1 / 7 per day . second one worked for 5 days @ rate = 1 / x per day expression : days * rate = work 5 * 1 / 7 + 5 * 1 / x = 1 5 x + 35 = 7 x 2 x = 35 x = 17.5 days . ans : d
Answer: D