There were 257 yellow, silver and white notebooks in a box. 19 white notebooks were removed from the box and the ratio of the number of yellow notebooks to the number of silver notebooks to the number of white notebooks became 2 : 5 : 7. Then some brown notebooks were added and the ratio of the number of white notebooks to the number of brown notebooks was 7 : 6.

1. What was the ratio of the number of yellow notebooks to the number of silver notebooks to the number of white notebooks at first?
2. How many notebooks were in the box in the end?

	Yellow	Silver	White	Brown	Total
Before	2 u	5 u	7 u + 19	0	257
Change 1	No change	No change	- 19		- 19
After 1	2 u	5 u	7 u		238
Change 2	No change	No change	No change	+ 6 u
After 2	2 u	5 u	7 u	6 u

(a)
Total number of notebooks at first
= 2 u + 5 u + 7 u + 19
= 14 u + 19

14 u + 19 = 257
14 u = 257 - 19
14 u = 238

1 u = 238 ÷ 14 = 17

Number of yellow notebooks at first
= 2 u
= 2 x 17
= 34

Number of silver notebooks at first
= 5 u
= 5 x 17
= 85

Number of white notebooks at first
= 7 u + 19
= 7 x 17 + 19
= 138 

At first
Yellow notebooks : Silver notebooks : White notebooks
34 : 85 : 138

(b)
Total number of notebooks in the box in the end
= 2 u + 5 u + 7 u + 6 u
= 20 u
= 340

Answer(s): (a) 34 : 85 : 138; (b) 340