Working individually, Jane can bake cakes for 4 hours and Roy can bake cakes in 5 hours. If Jane and Roy work together but independently at the task for 2 hours, at which point Roy leaves, how many remaining hours will it take Jane to complete the task alone?	Choose the correct choice:	A) 1 / 2	B) 2 / 5	C) 3 / 4	D) 1 / 4	E) 1 / 5

Rationale: in first 2 hrs roy will finish 2 / 5 = 2 / 5 of work and jane will finish 2 / 4 work so total 2 / 5 + 1 / 2 = 9 / 10 work is finished and 1 - 9 / 10 = 1 / 10 work remaining . now jane will take ( 1 / 10 ) * 4 = 2 / 5 hrs to finish it . so answer is b .
Answer: B