In a store, 3 pencils and 4 notebooks cost $15.80. Joseph bought 4 pencils and 5 notebooks at $20.60 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.
3 P + 4 N = 15.80 --- (1)
4 P + 5 N = 20.60 --- (2)
(2) - (1)
1 P + 1 N = 20.60 --- 15.80
1 P + 1 N = 4.80 --- (3)
Cost of 1 pencil and 1 notebook = $4.80
(b)
(3)
x3 3 P + 3 N = 14.40 --- (4)
(1) - (4)
1 N = 15.80 - 14.40 = $1.40
Cost of 1 notebook = $1.40
Answer(s): (a) $4.80; (b) $1.40