In a stationery shop, 3 pens and 4 notebooks cost $18.30. Joseph bought 4 pens and 5 notebooks at $23.70 from the book shop.
- Find the cost of 1 pen and 1 notebook.
- What was the cost of 1 notebook?
(a)
Let 1 pen be 1 P.
Let 1 notebook be 1 N.
3 P + 4 N = 18.30 --- (1)
4 P + 5 N = 23.70 --- (2)
(2) - (1)
1 P + 1 N = 23.70 --- 18.30
1 P + 1 N = 5.40 --- (3)
Cost of 1 pen and 1 notebook = $5.40
(b)
(3)
x3 3 P + 3 N = 16.20 --- (4)
(1) - (4)
1 N = 18.30 - 16.20 = $2.10
Cost of 1 notebook = $2.10
Answer(s): (a) $5.40; (b) $2.10