In a book shop, 3 notebooks and 4 pencils cost $23.90. Joseph bought 4 notebooks and 5 pencils at $30.60 from the book shop.
- Find the cost of 1 notebook and 1 pencil.
- What was the cost of 1 pencil?
(a)
Let 1 notebook be 1 N.
Let 1 pencil be 1 P.
3 N + 4 P = 23.90 --- (1)
4 N + 5 P = 30.60 --- (2)
(2) - (1)
1 N + 1 P = 30.60 --- 23.90
1 N + 1 P = 6.70 --- (3)
Cost of 1 notebook and 1 pencil = $6.70
(b)
(3)
x3 3 N + 3 P = 20.10 --- (4)
(1) - (4)
1 P = 23.90 - 20.10 = $3.80
Cost of 1 pencil = $3.80
Answer(s): (a) $6.70; (b) $3.80