The ratio of investments of two partners P and Q is 7:5 and the ratio of their profits is 7:10. If P invested the money for 20 months, find for how much time did Q invest the money?  Choose the correct choice from the following choices:
A) 11
B) 40
C) 18
D) 16
E) 12

Rationale: "7 * 5 : 20 * x = 7 : 10 x = 40 answer : b"
Answer: B