Question

A and B can do a peace of work in 35 days, while A alone can do it in the 60 days. How long would B take to do it​

Answer 1

Given,

$A$ and $B$ can do a peace of work in $35$ days, while $A$ alone can do it in the $60$ days.

We have find how long would $B$ take to do it

Let, $B$ alone can do in $x$ days

Now,

$\frac{1}{35}$ $= \frac{1}{60}+\frac{1}{x}$

We have to find the value of $x$

We have to move variable terms are LHS side and Constants terms are RHS side

$\frac{1}{x}= \frac{1}{35}-\frac{1}{60}$

$\frac{1}{x}= \frac{60-35}{35\times60}$

$\frac{1}{x}= \frac{25}{2100}$

$x= \frac{2100}{25}$

$x=84$

Therefore, $B$ alone can do in $84$ days.

Answer 2

As per data given in the question,

We have to determine that in how many days B alone can finish the work.

From the data,

It is given that,

A and B can do a peace of work in 35 days, while A alone can do it in the 60 days.

Let, B alone can do in x days

So, we can write it as,

$\frac{1}{35} = \frac{1}{60}+\frac{1}{x}$

As we have to find the value of x  

So, for solving the value of x we will separate the like terms at one side, So, we will shift the variable terms are LHS side and Constants terms are RHS side.

Hence, we will get it as,  

$\frac{1}{x}= \frac{1}{35}-\frac{1}{60}\\\frac{1}{x}= \frac{60-35}{35\times60}\\\frac{1}{x}= \frac{25}{2100}\\x= \frac{2100}{25}\\x=84\:days$  

Therefore, B alone can do in 84 days.