The number of green markers is four times the number of yellow markers. The number of yellow markers is 8 more than the number of purple markers. The total number of markers is 118. The cost of each green marker is $3.90 and the cost of each purple marker is $2.20. The total cost of all the markers is $400.30.

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

(a)
Number of purple markers = 1 u
Number of yellow markers = 1 u + 8

Number of green markers
= 4(1 u + 8)
= 4 u + 32

Total of number of markers
= 1 u + 1 u + 8 + 4 u + 32
= 6 u + 40

6 u + 40 = 118
6 u = 118 - 40
6 u = 78

1 u = 78 ÷ 6 = 13

Number of purple markers
= 1 u
= 13

(b)
Number of purple markers = 13

Number of yellow markers
=  13 + 8
= 21

Number of green markers
= 4 x 21
= 84

Cost of purple markers 
= 13 x 2.20
= $28.60

Cost of green markers 
= 84 x 3.90
= $327.60

Cost of yellow markers
= 400.30 - 327.60 - 28.60
= $44.10

Cost of 1 yellow marker
= 44.10 ÷ 21
= $2.10

Answer(s) (a) 13; (b) $2.10