A and B can do a piece of work in 10 days and 15 days respectively. They started the work together but B left after sometime and A finished the remaining work in 5 days. After how many days from the start did B leave ?

Explanation

To solve the problem step by step, we will first determine the work rates of A and B, then calculate how much work they completed together before B left, and finally find out how many days B worked before leaving.

### Step 1: Determine the work rates of A and B
- A can complete the work in 10 days. Therefore, A's work rate is:
\[ \text{Work rate of A} = \frac{1}{10} \text{ (work per day)} \]
- B can complete the work in 15 days. Therefore, B's work rate is:
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