In a shop, 4 files and 5 notebooks cost $16.10. Joseph bought 5 files and 6 notebooks at $19.70 from the book shop.
- Find the cost of 1 file and 1 notebook.
- What was the cost of 1 notebook?
(a)
Let 1 file be 1 F.
Let 1 notebook be 1 N.
4 F + 5 N = 16.10 --- (1)
5 F + 6 N = 19.70 --- (2)
(2) - (1)
1 F + 1 N = 19.70 --- 16.10
1 F + 1 N = 3.60 --- (3)
Cost of 1 file and 1 notebook = $3.60
(b)
(3)
x4 4 F + 4 N = 14.40 --- (4)
(1) - (4)
1 N = 16.10 - 14.40 = $1.70
Cost of 1 notebook = $1.70
Answer(s): (a) $3.60; (b) $1.70