Question 23
A painting job is shared by four sisters who all paint at the same rate. After Alice finishes 1/4 of the job, Beth comes in and finishes 2/3 of what is left. Then Cathy comes in and finishes 3/4 of what remains. The last part of the job is finished by Dee, who completes her part in 20 minutes. What was the total length of time, in minutes, for the whole job to be completed?