The ratio of the number of ducks in Farm B to the number of ducks in Farm C was 4 : 7. There were 45 fewer ducks in Farm B than in Farm C. When 10 ducks escaped from Farm C, the farmer in Farm C bought another 13 ducks. What was the new ratio of the number of ducks in Farm B to the number of ducks in Farm C in the end? Give your answer in the simplest form.
| |
Farm B |
Farm C |
| Before |
4 u |
7 u |
| Change 1 |
|
- 10 |
| Change 2 |
|
+ 13 |
| After |
4 u |
7 u + 3 |
Number of fewer ducks in Farm B than Farm C
= 7 u - 4 u
= 3 u
3 u = 45
1 u = 45 ÷ 3 = 15
Number of ducks in Farm B
= 4 u
= 15 x 4
= 60
Number of ducks in Farm C
= 7 u
= 15 x 7
= 105
New number of ducks in Farm C
= 7 u + 3
= 105 + 3
= 108
Farm B : Farm C
60 : 108
(÷ 12)5 : 9
Answer(s): 5 : 9
