The number of orange files is thrice the number of yellow files. The number of yellow files is 9 more than the number of blue files. The total number of files is 106. The cost of each orange file is $4.20 and the cost of each blue file is $3.30. The total cost of all the files is $375.10.
- Find the number of blue files.
- Find the cost of a yellow file.
(a)
Number of blue files = 1 u
Number of yellow files = 1 u + 9
Number of orange files
= 3(1 u + 9)
= 3 u + 27
Total of number of files
= 1 u + 1 u + 9 + 3 u + 27
= 5 u + 36
5 u + 36 = 106
5 u = 106 - 36
5 u = 70
1 u = 70 ÷ 5 = 14
Number of blue files
= 1 u
= 14
(b)
Number of blue files = 14
Number of yellow files
= 14 + 9
= 23
Number of orange files
= 3 x 23
= 69
Cost of blue files
= 14 x 3.30
= $46.20
Cost of orange files
= 69 x 4.20
= $289.80
Cost of yellow files
= 375.10 - 289.80 - 46.20
= $39.10
Cost of 1 yellow file
= 39.10 ÷ 23
= $1.70
Answer(s) (a) 14; (b) $1.70
