The number of red markers is twice the number of purple markers. The number of purple markers is 10 more than the number of brown markers. The total number of markers is 118. The cost of each red marker is $2.80 and the cost of each brown marker is $1.80. The total cost of all the markers is $276.40.

1. Find the number of brown markers.
2. Find the cost of a purple marker.

(a)
Number of brown markers = 1 u
Number of purple markers = 1 u + 10

Number of red markers
= 2(1 u + 10)
= 2 u + 20

Total of number of markers
= 1 u + 1 u + 10 + 2 u + 20
= 4 u + 30

4 u + 30 = 118
4 u = 118 - 30
4 u = 88

1 u = 88 ÷ 4 = 22

Number of brown markers
= 1 u
= 22

(b)
Number of brown markers = 22

Number of purple markers
=  22 + 10
= 32

Number of red markers
= 2 x 32
= 64

Cost of brown markers 
= 22 x 1.80
= $39.60

Cost of red markers 
= 64 x 2.80
= $179.20

Cost of purple markers
= 276.40 - 179.20 - 39.60
= $57.60

Cost of 1 purple marker
= 57.60 ÷ 32
= $1.80

Answer(s) (a) 22; (b) $1.80