An oil tank has two pipes connected to it. If the tank is empty, Pipe A can fill it in 2 hours. If the tank is full, Pipe B can empty it in 3 hours. If both pipes are activated at the same time when the tank in empty, how many hours will it take for the tank to be filled to 60% capactiy.
a) 2.4
b) 3.6
c) 6
d) 60
