Question

Nancy can do a typing job in 8 hours, when Carole helps her, they can do the job in 5 hours. How many hours would it take Carole to do it alone

Answer 1

Answer: $\frac{40}{3}\ \text{hours}$

Step-by-step explanation:

Nancy can do typing job in 8 hours

i.e. in 1-hour nancy can  $\frac{1}{8}$ part of work

Together they can do that work in 5 hours

or in 1 hour $\frac{1}{5}$ part of work is done

suppose Carole takes x hours for the work

so, in 1 hour $\frac{1}{x}$ part is done

If both work together for 1 hour then we can write

$\frac{1}{8}+\frac{1}{x}=\frac{1}{5}$

$\frac{1}{x}=\frac{1}{5}-\frac{1}{8}$

$x=\frac{40}{3}\ \text{hours}$