P is 50% more efficient than Q. P can complete a work in 25 days. If P and Q work together, how many days will it take to complete the same work?	Answers
A) 11
B) 13
C) 15
D) 17
E) 19

Rationale: "the work done by p in 1 day = 1 / 25 let work done by q in 1 day = q q × ( 150 / 100 ) = 1 / 25 q = 100 / ( 25 × 150 ) = 10 / ( 25 × 15 ) the work done by p and q in 1 day = 1 / 25 + 10 / ( 25 × 15 ) = 25 / ( 25 × 15 ) = 1 / 15 p and q together can do the work in 15 days . the answer is c ."
Answer: C