Question

A can do piece of work in 20 days and b can do it 30 days how long will they take if they work together

Answer 1

Solutions :-


'A' can do a piece of work in 20 days
A's one day work = 1/20

'B' can do same work in 30 days
B's one day work = 1/30


Find the (A' and 'B')'s one day work :-

$= \frac{1}{20 } + \frac{1}{30} \\ \\ = \frac{3 \: \: + \: \: 2}{60} \\ \\ = \frac{5}{60} = \frac{1}{12}$

Find the number of days to complete a work :-

By unitary method,

1/12 work = 1 days
1 work = 1 × 12 days = 12 days



Hence,
A' and 'B' can complete a work in 12 days.

Answer 2

Here is your solution

Given:-

A can do a piece of work in 20 days

I.e

one day work = 1/20

B can do same work in 30 days.

I. e
one day work = 1/30

To Find the (A and B) one day work :-

1/20 + 1/30 =5/60=1/12

To Find the number of days to complete a work :-

Now
using By unitary method:-

1/12 work = 1 days

1 work = 1 × 12 days = 12 days

Hence,

A and B can complete a work in 12 days.

Hope it helps you