It takes Alice $25$ minutes to clean her room. It takes Bob $\frac{2}{5}$ of that amount of time to clean his room. How many minutes does it take Bob to clean his room?
To solve this problem, I need to find out how much time $\frac{2}{5}$ of $25$ minutes is. I can do this by multiplying $\frac{2}{5}$ by $25$, which is the same as dividing $25$ by $5$ and then multiplying by $2$. Dividing $25$ by $5$ gives me $5$, and multiplying $5$ by $2$ gives me $10$. Therefore, it takes Bob $10$ minutes to clean his room. 