Eva had four containers, C, D, E and F which contained a total of 335 apples. She transferred 22 apples from Container C to Container D, 74 apples from Container D to Container E and 168 apples from Container E to Container F. The ratio of the number of apples in Container C to Container D to Container E changed from  2 : 5 : 9 to 1 : 4 : 7. How many apples were in Container F at first?

	Make p the same (1)x4 = (3)	C (1)	D (2)	E	F
Before	8 u	2 u	5 u	9 u	?
Change 1	- 88	- 22	+ 22
Change 2			- 74	+ 74
Change 3				- 168	+ 168
After	4 p	1 p	4 p	7 p	?

2 u - 22 = 1 p --- (1)

5 u + 22 - 74 = 4 p
5 u - 52 = 4 p --- (2)

(1) _{x 4}
8 u - 88 = 4 p --- (3)

Make p the same.

(3) = (2)
8 u - 88 = 5 u - 52
8 u - 5 u = 88 - 52
3 u = 36

1 u = 36 ÷ 3 = 12

Total number of apples in Container C, Container D and Container E
= 2 u + 5 u + 9 u
= 16 u

Total number of apples in Container F at first
= 335 - 16 u
= 335 - 16 x 12
= 335 - 192
= 143

Answer(s): 143