The compound ratio of 3:4, 3:2 and 4:5?  Choices.
A) 1 : 9  B) 1 : 7  C) 1 : 2  D) 9 : 10  E) 1 : 4

Rationale: "3 / 4 * 3 / 2 * 4 / 5 = 9 / 10 = 9 : 10 answer : d"
Answer: D