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 the correct choice
A) 3:4
B) 5:6
C) 7:8
D) 9:10
E) 11:12
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 9:10.
<result>D</result>
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...?