Question

A B and C can do a piece of work in 15 12 20 days respectively they started the work together but she left after 2 days in how many days will be the remaining work be completed by a and b​

Answer 1

Step by step explanation:-

a can do = 15 days

b can do = 12 days

Total work = 15 + 12 + 20 = 47

a and b can do = (15 - 2) + (12 - 2)

= 13 + 10 = 23

Answer:-23

Answer 2

Correct question:

→ A, B and C can do a piece of work in 15, 12 and 12 days, respectively.They started the work together but C left after 2 days. In how many days will be the remaining work be completed by a and b ?

$\bf{\huge{\underline{\boxed{\sf\purple{Answer\: : 4\:days}}}}}$

$\textsf{\underline{\underline{Step-by-Step-Explanation}}}$

On the 1st day of the work,

Total work done by A, B and C = $\dfrac{1}{15} + \dfrac{1}{12} + \dfrac{1}{20}$

( Take the LCM of 15, 12 and 20 )

L.C.M = 60

Now,

We get,

= $\dfrac{12}{60}$

= $\dfrac{1}{5}$

Therefore,

On the 2nd day of work,

A, B and C  would have done $\dfrac{2}{5}$ work.

For A and B ( on the first day of work ) :

= $\dfrac{1}{12} + \dfrac{1}{15}$

( Take L.C.M of 12 and 15 )

= $\dfrac{9}{60}$

Now,

It remains for $\dfrac{3}{5}$ of the work.

= $\dfrac{3}{5}$ ÷ $\dfrac{9}{60}$

= $\dfrac{3}{5}$ × $\dfrac{60}{9}$

= 4

Answer : 4 days will be the remaining work to be done by A and B

$\huge\mathscr\red{Be\:Brainly!!!}$