A total of 50 white folders and grey folders are in a container. The ratio of white folders to grey folders was 1 : 4. Some silver folders and blue folders were put into the container. For every 2 grey folders that were already in the container, 2 blue ones were added. Then, the final number of white folders and silver folders was ¹₂ the final number of grey folders and blue folders. Find the total number of silver and blue folders.

Silver folders	White folders	Grey folders	Blue folders
	1x1	4x1
		2x2	2x2
1x4		2x4
3 u	1 u	4 u	4 u

The number of grey folders is repeated.  Make the number of grey folders the same.  LCM of 4 and 2 is 4.

The total number of grey folders and blue folders is repeated.  Make the total number of grey and blue folders the same.  LCM of 8 and 2 is 8.

Total number of white folders and grey folders
= 1 u + 4 u
= 5 u

5 u = 50

1 u = 50 ÷ 5 = 10

Total number of silver and blue folders
= 3 u + 4 u
= 7 u
= 7 x 10
= 70

Answer(s): 70