Min had four boxes, J, K, L and M which contained a total of 340 kiwis. She transferred 12 kiwis from Box J to Box K, 21 kiwis from Box K to Box L and 54 kiwis from Box L to Box M. The ratio of the number of kiwis in Box J to Box K to Box L changed from  1 : 2 : 4 to 1 : 5 : 7. How many kiwis were in Box M at first?

	Make p the same (1)x5 = (3)	J (1)	K (2)	L	M
Before	5 u	1 u	2 u	4 u	?
Change 1	- 60	- 12	+ 12
Change 2			- 21	+ 21
Change 3				- 54	+ 54
After	5 p	1 p	5 p	7 p	?

1 u - 12 = 1 p --- (1)

2 u + 12 - 21 = 5 p
2 u - 9 = 5 p --- (2)

(1) _{x 5}
5 u - 60 = 5 p --- (3)

Make p the same.

(3) = (2)
5 u - 60 = 2 u - 9
5 u - 2 u = 60 - 9
3 u = 51

1 u = 51 ÷ 3 = 17

Total number of kiwis in Box J, Box K and Box L
= 1 u + 2 u + 4 u
= 7 u

Total number of kiwis in Box M at first
= 340 - 7 u
= 340 - 7 x 17
= 340 - 119
= 221

Answer(s): 221