One pipe can fill a tank in 20 minutes, while another takes 30 minutes to fill the same tank. How long would it take the two pipes together to fill the tank?
in 1 min pipe A can fill 1/20 part of a tank in 1 min pipe B can fill 1/30 part of a tank in 1 min working together the two pipes can fill 1/20 +1/30 part a tank, which is 5/60 = 1/12 thus they will take 12/1 = 12 mins to fill the tank
