A total of 6 silver folders and blue folders are in a container. The ratio of silver folders to blue folders was 1 : 2. Some yellow folders and purple folders were put into the container. For every 1 blue folders that were already in the container, 13 purple ones were added. Then, the final number of silver folders and yellow folders was ²₇ the final number of blue folders and purple folders. Find the total number of yellow and purple folders.

Yellow folders	Silver folders	Blue folders	Purple folders
	1x1	2x1
		1x2	13x2
2x4		7x4
7 u	1 u	2 u	26 u

The number of blue folders is repeated.  Make the number of blue folders the same.  LCM of 2 and 1 is 2.

The total number of blue folders and purple folders is repeated.  Make the total number of blue and purple folders the same.  LCM of 28 and 7 is 28.

Total number of silver folders and blue folders
= 1 u + 2 u
= 3 u

3 u = 6

1 u = 6 ÷ 3 = 2

Total number of yellow and purple folders
= 7 u + 26 u
= 33 u
= 33 x 2
= 66

Answer(s): 66