Question

Mia and holly can clean their room in 20 minutes, working together. Working alone, mia can clean the room in 30. How long would it take holly to clean alone?

Answer 1

Answer:  Holly would take 60 minutes to clean alone.

Step-by-step explanation:

Let t = Time taken by Holly to clean alone.

Given: Time taken by Mia to clean alone = 30 minutes

Time taken by Mia and holly to clean their room = 20 minutes

Then,

$\dfrac1t+\dfrac{1}{30}=\dfrac{1}{20}\\\\\Rightarrow\ \dfrac{1}{t}=\dfrac{1}{20}-\dfrac{1}{30}\\\\\Rightarrow\ \dfrac{1}{t}=\dfrac{3-2}{60}\\\\\Rightarrow\ \dfrac{1}{t}=\dfrac{1}{60}\\\\\Rightarrow\ t= 60$

Hence, Holly would take 60 minutes to clean alone.