The ratio of the number of chickens in Farm Z to the number of chickens in Farm A was 5 : 8. There were 42 fewer chickens in Farm Z than in Farm A. When 9 chickens escaped from Farm A, the farmer in Farm A bought another 17 chickens. What was the new ratio of the number of chickens in Farm Z to the number of chickens in Farm A in the end? Give your answer in the simplest form.

	Farm Z	Farm A
Before	5 u	8 u
Change 1		- 9
Change 2		+ 17
After	5 u	8 u + 8

Number of fewer chickens in Farm Z than Farm A
= 8 u - 5 u
= 3 u

3 u = 42

1 u = 42 ÷ 3 = 14

Number of chickens in Farm Z
= 5 u
= 14 x 5
= 70

Number of chickens in Farm A
= 8 u
= 14 x 8
= 112

New number of chickens in Farm A
= 8 u + 8
= 112 + 8
= 120

Farm Z : Farm A
70 : 120 _{(÷ 10)}
7 : 12

Answer(s): 7 : 12