Question

A can do a work in 16 days and b can do that in 24 days. they started together but b left the work 6 days before the work finished. then calculate time required to finsh the work.

Answer 1

The rate of A 120120 job per day;
The rate of B 130130 job per day.

Say they need tt days to complete the project. 

According to the stem we have that B works for all tt days and A works only for t−10t−10 days, thus 120∗(t−10)+130∗t=1120∗(t−10)+130∗t=1 --> t=18t=18days