If Ben can mix 20 drinks in 5 minutes, Mary can mix 20 drinks in 10 minutes, and Harry can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mix the 20 drinks?
3 minutes and 46 seconds
3 minutes and 44 seconds
2 minutes and 46 seconds
2 minutes and 44 seconds