P and Q are the only two applicants qualified for a short-term research project that pays 540 dollars in total. Candidate P has more experience and, if hired, would be paid 50 percent more per hour than candidate Q would be paid. Candidate Q, if hired, would require 10 hours more than candidate P to do the job. Candidate P’s hourly wage is how many dollars greater than candidate Q’s hourly wage? Choose the correct choice from the following answers.
A) $ 9 B) $ 15 C) $ 18 D) $ 21 E) $ 27

Rationale: "let q ' s hourly wage be x , then p ' s hourly wage is 1.5 x let t be the number of hours that q needs , then p needs t - 10 hours to do the job . since they both are paid an equal total amount of $ 540 : x * t = 1.5 x * ( t - 10 ) t = 30 hours and q ' s hourly wage is 540 / 30 = $ 18 p ' s hourly wage is 540 / ( t - 10 ) = $ 27 which is $ 9 per hour more . the answer is a ."
Answer: A