Two pipes A and B can fill a tank in 12 minutes and 18 minutes respectively. If both the pipes are opened simultaneously, how long will they take to fill the tank ?

Explanation

To solve the problem of how long it will take for pipes A and B to fill the tank when opened simultaneously, we can follow these steps:

### Step 1: Determine the rate of each pipe
- Pipe A can fill the tank in 12 minutes. Therefore, in 1 minute, Pipe A fills \( \frac{1}{12} \) of the tank.
- Pipe B can fill the tank in 18 minutes. Therefore, in 1 minute, Pipe B fills \( \frac{1}{18} \) of the tank.

### Step 2: Add the rates of both pipes
- When both pipes are opened together, their combined rate of filling the tank per minute is:
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