The marks obtained by Polly and Sandy are in the ratio 3:5 and those obtained by Sandy and Willy are in the ratio of 3:2. The marks obtained by Polly and Willy are in the ratio of...?	Choose one
A) 3 : 4  B) 5 : 6  C) 7 : 8  D) 9 : 10  E) 11 : 12

Rationale: "polly : sandy = 3 : 5 = 9 : 15 sandy : willy = 3 : 2 = 15 : 10 polly : sandy : willy = 9 : 15 : 10 polly : willy = 9 : 10 the answer is d ."
Answer: D