In a bookstore, 3 markers and 4 pens cost $9.80. Joseph bought 4 markers and 5 pens at $12.70 from the book shop.
- Find the cost of 1 marker and 1 pen.
- What was the cost of 1 pen?
(a)
Let 1 marker be 1 M.
Let 1 pen be 1 P.
3 M + 4 P = 9.80 --- (1)
4 M + 5 P = 12.70 --- (2)
(2) - (1)
1 M + 1 P = 12.70 --- 9.80
1 M + 1 P = 2.90 --- (3)
Cost of 1 marker and 1 pen = $2.90
(b)
(3)
x3 3 M + 3 P = 8.70 --- (4)
(1) - (4)
1 P = 9.80 - 8.70 = $1.10
Cost of 1 pen = $1.10
Answer(s): (a) $2.90; (b) $1.10