The number of yellow folders is thrice the number of brown folders. The number of brown folders is 7 more than the number of purple folders. The total number of folders is 138. The cost of each yellow folder is $2.90 and the cost of each purple folder is $2.40. The total cost of all the folders is $383.40.
- Find the number of purple folders.
- Find the cost of a brown folder.
(a)
Number of purple folders = 1 u
Number of brown folders = 1 u + 7
Number of yellow folders
= 3(1 u + 7)
= 3 u + 21
Total of number of folders
= 1 u + 1 u + 7 + 3 u + 21
= 5 u + 28
5 u + 28 = 138
5 u = 138 - 28
5 u = 110
1 u = 110 ÷ 5 = 22
Number of purple folders
= 1 u
= 22
(b)
Number of purple folders = 22
Number of brown folders
= 22 + 7
= 29
Number of yellow folders
= 3 x 29
= 87
Cost of purple folders
= 22 x 2.40
= $52.80
Cost of yellow folders
= 87 x 2.90
= $252.30
Cost of brown folders
= 383.40 - 252.30 - 52.80
= $78.30
Cost of 1 brown folder
= 78.30 ÷ 29
= $2.70
Answer(s) (a) 22; (b) $2.70
