In a bookstore, 4 pencils and 5 notebooks cost $19.70. Joseph bought 5 pencils and 6 notebooks at $23.90 from the book shop.
- Find the cost of 1 pencil and 1 notebook.
- What was the cost of 1 notebook?
(a)
Let 1 pencil be 1 P.
Let 1 notebook be 1 N.
4 P + 5 N = 19.70 --- (1)
5 P + 6 N = 23.90 --- (2)
(2) - (1)
1 P + 1 N = 23.90 --- 19.70
1 P + 1 N = 4.20 --- (3)
Cost of 1 pencil and 1 notebook = $4.20
(b)
(3)
x4 4 P + 4 N = 16.80 --- (4)
(1) - (4)
1 N = 19.70 - 16.80 = $2.90
Cost of 1 notebook = $2.90
Answer(s): (a) $4.20; (b) $2.90