Question

Raja can do a piece of work in 14 days, while rani can do the same work in 21 days. they started the work together but 3 days before the completion of the work, raja left the work. the total number of days to complete the work is

Answer 1

Raja's 1 day work = 1/14
Rani's 1 day work = 1/21
Raja and Rani 1 day work = 1/14 + 1/21 = 5/42
Raja and Rani 3 day work = 15/42
Rani takes to complete in 15/42 ÷ 1/21 = 15/2 days
Total days taken to complete = 42/5 + 15/2 - 3 = (84 + 75 - 30)/10 = 129/10 = 12.9 days

Answer 2

Answer:

Let the total no. of days needed to complete the work be x days.

Let's assume total work to be 1.

1 day work of A = 1/14 unit

1 day work of B = 1/21 unit.

Since A leaves 3 days before completion of work, therefore A works for (x-3) days.

And B works for x days.

According to the question,

(1/4)×(x-3)+(1/21)×x=1

3x-9+2x=42

5x=51

x=10.2 days.

So total days needed to complete the work = 10.2 days.

Step-by-step explanation: