Problema Solution

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 4 more days. How many days would it have taken the second carpenter to do the complete job working alone?

Answer provided by our tutors

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 4 days @ rate=1/x per day

Expression:

Days*Rate=Work

5*1/7+4*1/x=1

5x+28=7x

2x=28

x=14 days.