In a store, 3 notebooks and 4 pens cost $20.90. Joseph bought 4 notebooks and 5 pens at $26.60 from the book shop.
- Find the cost of 1 notebook and 1 pen.
- What was the cost of 1 pen?
(a)
Let 1 notebook be 1 N.
Let 1 pen be 1 P.
3 N + 4 P = 20.90 --- (1)
4 N + 5 P = 26.60 --- (2)
(2) - (1)
1 N + 1 P = 26.60 --- 20.90
1 N + 1 P = 5.70 --- (3)
Cost of 1 notebook and 1 pen = $5.70
(b)
(3)
x3 3 N + 3 P = 17.10 --- (4)
(1) - (4)
1 P = 20.90 - 17.10 = $3.80
Cost of 1 pen = $3.80
Answer(s): (a) $5.70; (b) $3.80