Is that Chole and Dave each get 2.5 times Ann? Let's assume so.
A:B=2 : 9
A:C:D=1 : 2.5 : 2.5
We can scale ratios without changing them, like fractions.
A:C:D=2:5:5
With A the same in both ratios we can put them together.
A:B:C:D=2:9:5:5
There's some scale factor k such that
k(2+9+5+5)=399
k = 399/21 = 19
Bill gets 9 shares of 19, 9×19 = 171
Answer: 171 pounds
