SAT Quant : Word Problem in Work and Time

Work Time is a topic in which quite a few interesting word problems are found.

Two typists are engaged to type 720 pages. Typist A takes 11 more hours than typist B to type 720 pages. If typist B types 20% more pages per hour than typist A, in how many hours will the task be completed if both A and B work together on the task?
A. 330 hours
B. 66 hours
C. 30 hours
D. 55 hours
E. 11 hours