A can complete a project in 20 days and B can complete the same project in 30 days. If A and B start working on the project together and B quits 5 days before the project is completed, in how many days total will the project be completed? Pick.
A) 10  B) 12  C) 14  D) 16  E) 18
A's rate is 1/20 of the project per day.   B's rate is 1/30 of the project per day.   The combined rate is 1/12 of the project per day.   In the last 5 days, A can do 1/4 of the project.   Thus A and B must complete 3/4 of the project, which takes 9 days.   The total number of days is  9 + 5= 
<gadget id="calculator"> 9 + 5</gadget>
<output>14</output>
14.   The answer is 14.
<result>C</result>
A can complete a project in 20 days and B can complete the same project in 30 days. If A and B start working on the project together and B quits 5 days before the project is completed, in how many days total will the project be completed?