A can complete a project in \(20\) days and \(B\) can complete the same project in \(30\) days. If \(A\) and \(B\) start

[Vincen]

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 \(A\) quits \(10\) days before the project is completed, in how many days will the project be completed?

(A) 18 days
(B) 27 days
(C) 26.67 days
(D) 16 days
(E) 12 days

Answer: A

Source: GMAT Paper Tests