Toni and Michael are cleaning for a rental inspection. Toni takes an exponentially distributed amount of time with mean a hours to clean the kitchen. Michael takes an exponentially distributed amount of time with mean A hours to clean the bathroom. Once one of them is finished they go to the garden and chop down the weeds which takes an exponentially distributed amount of time with mean 1 hour. When the second person is done inside they go help the other outside, which increases the chopping rate by 2. What is the mean time until all the work is done