A total of 25 black pencils and silver pencils are in a container. The ratio of black pencils to silver pencils was 1 : 4. Some white pencils and yellow pencils were put into the container. For every 2 silver pencils that were already in the container, 10 yellow ones were added. Then, the final number of black pencils and white pencils was ³₈ the final number of silver pencils and yellow pencils. Find the total number of white and yellow pencils.

White pencils	Black pencils	Silver pencils	Yellow pencils
	1x1	4x1
		2x2	10x2
3x3		8x3
8 u	1 u	4 u	20 u

The number of silver pencils is repeated.  Make the number of silver pencils the same.  LCM of 4 and 2 is 4.

The total number of silver pencils and yellow pencils is repeated.  Make the total number of silver and yellow pencils the same.  LCM of 24 and 8 is 24.

Total number of black pencils and silver pencils
= 1 u + 4 u
= 5 u

5 u = 25

1 u = 25 ÷ 5 = 5

Total number of white and yellow pencils
= 8 u + 20 u
= 28 u
= 28 x 5
= 140

Answer(s): 140