Linda had four containers, J, K, L and M which contained a total of 180 oranges. She transferred 5 oranges from Container J to Container K, 10 oranges from Container K to Container L and 30 oranges from Container L to Container M. The ratio of the number of oranges in Container J to Container K to Container L changed from  2 : 5 : 11 to 1 : 4 : 7. How many oranges were in Container M at first?

	Make p the same (1)x4 = (3)	J (1)	K (2)	L	M
Before	8 u	2 u	5 u	11 u	?
Change 1	- 20	- 5	+ 5
Change 2			- 10	+ 10
Change 3				- 30	+ 30
After	4 p	1 p	4 p	7 p	?

2 u - 5 = 1 p --- (1)

5 u + 5 - 10 = 4 p
5 u - 5 = 4 p --- (2)

(1) _{x 4}
8 u - 20 = 4 p --- (3)

Make p the same.

(3) = (2)
8 u - 20 = 5 u - 5
8 u - 5 u = 20 - 5
3 u = 15

1 u = 15 ÷ 3 = 5

Total number of oranges in Container J, Container K and Container L
= 2 u + 5 u + 11 u
= 18 u

Total number of oranges in Container M at first
= 180 - 18 u
= 180 - 18 x 5
= 180 - 90
= 90

Answer(s): 90