There were 196 blue, black and brown notebooks in a box. 16 brown notebooks were removed from the box and the ratio of the number of blue notebooks to the number of black notebooks to the number of brown notebooks became 3 : 2 : 7. Then some yellow notebooks were added and the ratio of the number of brown notebooks to the number of yellow notebooks was 7 : 4.

1. What was the ratio of the number of blue notebooks to the number of black notebooks to the number of brown notebooks at first?
2. How many notebooks were in the box in the end?

	Blue	Black	Brown	Yellow	Total
Before	3 u	2 u	7 u + 16	0	196
Change 1	No change	No change	- 16		- 16
After 1	3 u	2 u	7 u		180
Change 2	No change	No change	No change	+ 4 u
After 2	3 u	2 u	7 u	4 u

(a)
Total number of notebooks at first
= 3 u + 2 u + 7 u + 16
= 12 u + 16

12 u + 16 = 196
12 u = 196 - 16
12 u = 180

1 u = 180 ÷ 12 = 15

Number of blue notebooks at first
= 3 u
= 3 x 15
= 45

Number of black notebooks at first
= 2 u
= 2 x 15
= 30

Number of brown notebooks at first
= 7 u + 16
= 7 x 15 + 16
= 121 

At first
Blue notebooks : Black notebooks : Brown notebooks
45 : 30 : 121

(b)
Total number of notebooks in the box in the end
= 3 u + 2 u + 7 u + 4 u
= 16 u
= 240

Answer(s): (a) 45 : 30 : 121; (b) 240