There were 249 pink, black and blue notebooks in a box. 2 blue notebooks were removed from the box and the ratio of the number of pink notebooks to the number of black notebooks to the number of blue notebooks became 2 : 4 : 7. Then some gold notebooks were added and the ratio of the number of blue notebooks to the number of gold notebooks was 7 : 4.

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

	Pink	Black	Blue	Gold	Total
Before	2 u	4 u	7 u + 2	0	249
Change 1	No change	No change	- 2		- 2
After 1	2 u	4 u	7 u		247
Change 2	No change	No change	No change	+ 4 u
After 2	2 u	4 u	7 u	4 u

(a)
Total number of notebooks at first
= 2 u + 4 u + 7 u + 2
= 13 u + 2

13 u + 2 = 249
13 u = 249 - 2
13 u = 247

1 u = 247 ÷ 13 = 19

Number of pink notebooks at first
= 2 u
= 2 x 19
= 38

Number of black notebooks at first
= 4 u
= 4 x 19
= 76

Number of blue notebooks at first
= 7 u + 2
= 7 x 19 + 2
= 135 

At first
Pink notebooks : Black notebooks : Blue notebooks
38 : 76 : 135

(b)
Total number of notebooks in the box in the end
= 2 u + 4 u + 7 u + 4 u
= 17 u
= 323

Answer(s): (a) 38 : 76 : 135; (b) 323