Anna spent $138 on some notebooks, staplers and files. The number of notebooks she bought was ¹₄ the number of staplers. The number of files she bought was ¹₅ the number of staplers. The ratio of the amount of money she spent on the notebooks, staplers and files was 9 : 6 : 8. The staplers were sold at 5 for $9. Find the price of 1 notebook.

Amount spent
Notebooks	Staplers	Files	Total
9 u	6 u	8 u	$138

Total amount that Anna spent on notebooks, staplers and files
= 9 u + 6 u + 8 u
= 23 u

23 u = 138

1 u = 138 ÷ 23 = 6

Amount that Anna spent on staplers
= 6 u
= 6 x 6
= $36

Number of sets of staplers of 5 bought
= 36 ÷ 9
= 4

Number of staplers that Anna bought
= 4 x 5
= 20

Number of items bought
Notebooks	Staplers	Files	Total
1x5	4x5
	5x4	1x4
5 p	20 p	4 p	29 p

The number of staplers bought is repeated.  Make the number of staplers bought is the same.  LCM of 4 and 5 is 20.

Number of staplers that Anna bought = 20 p

20 p = 20

1 p = 20 ÷ 20 = 1

Number of notebooks that Anna bought
= 5 p
= 5 x 1
= 5

Amount that Anna spent on notebooks
= 9 u
= 9 x 6
= $54

Price of 1 notebook
= 54 ÷ 5
= $10.80

Answer(s): $10.80