Emily spent $100 on some markers, files and pens. The number of markers she bought was ¹₂ the number of files. The number of pens she bought was ⁴₅ the number of files. The ratio of the amount of money she spent on the markers, files and pens was 7 : 9 : 4. The files were sold at 4 for $9. Find the price of 1 marker.

Amount spent
Markers	Files	Pens	Total
7 u	9 u	4 u	$100

Total amount that Emily spent on markers, files and pens
= 7 u + 9 u + 4 u
= 20 u

20 u = 100

1 u = 100 ÷ 20 = 5

Amount that Emily spent on files
= 9 u
= 9 x 5
= $45

Number of sets of files of 4 bought
= 45 ÷ 9
= 5

Number of files that Emily bought
= 5 x 4
= 20

Number of items bought
Markers	Files	Pens	Total
1x5	2x5
	5x2	4x2
5 p	10 p	8 p	23 p

The number of files bought is repeated.  Make the number of files bought is the same.  LCM of 2 and 5 is 10.

Number of files that Emily bought = 10 p

10 p = 20

1 p = 20 ÷ 10 = 2

Number of markers that Emily bought
= 5 p
= 5 x 2
= 10

Amount that Emily spent on markers
= 7 u
= 7 x 5
= $35

Price of 1 marker
= 35 ÷ 10
= $3.50

Answer(s): $3.50