The number of purple markers is twice the number of blue markers. The number of blue markers is 8 more than the number of red markers. The total number of markers is 120. The cost of each purple marker is $3.60 and the cost of each red marker is $2.20. The total cost of all the markers is $369.60.

1. Find the number of red markers.
2. Find the cost of a blue marker.

(a)
Number of red markers = 1 u
Number of blue markers = 1 u + 8

Number of purple markers
= 2(1 u + 8)
= 2 u + 16

Total of number of markers
= 1 u + 1 u + 8 + 2 u + 16
= 4 u + 24

4 u + 24 = 120
4 u = 120 - 24
4 u = 96

1 u = 96 ÷ 4 = 24

Number of red markers
= 1 u
= 24

(b)
Number of red markers = 24

Number of blue markers
=  24 + 8
= 32

Number of purple markers
= 2 x 32
= 64

Cost of red markers 
= 24 x 2.20
= $52.80

Cost of purple markers 
= 64 x 3.60
= $230.40

Cost of blue markers
= 369.60 - 230.40 - 52.80
= $86.40

Cost of 1 blue marker
= 86.40 ÷ 32
= $2.70

Answer(s) (a) 24; (b) $2.70