Machine \(A\) takes \(10\) hours to complete a certain job and starts that job at \(9\)AM. After one hour of working

[Vincen]

Machine \(A\) takes \(10\) hours to complete a certain job and starts that job at \(9\)AM. After one hour of working alone, machine \(A\) is joined by machine \(B\) and together they complete the job at \(5\)PM. How long would it have taken machine \(B\) to complete the job if it had worked alone for the entire job?

(A) 15 hours
(B) 18 hours
(C) 20 hours
(D) 24 hours
(E) 35 hours

Answer: E

Source: Veritas Prep