Pipe A can fill a tank in 20 minutes, while pipe B takes 30 minutes to fill the same tank. If both pipes operate simultaneously, how many minutes will it take to fill the tank completely?

Explanation

Pipe A fills 1/20 of the tank per minute, and pipe B fills 1/30 per minute. Together, their combined rate is 1/20 + 1/30 = 1/12 of the tank per minute. Therefore, both pipes working together will fill the tank in 12 minutes.