If Adam buys 4 marbles and 5 beads, it costs $41.90.
If Adam buys 5 marbles and 4 beads, he will have $5.50 left.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
4 marbles + 5 beads = 41.90 --- (1)
5 marbles + 4 beads = 41.90 - 5.50 = 36.40 --- (2)
(1) + (2)
9 marbles + 9 beads = 78.30 --- (3)
(3)
÷ 9 1 marble + 1 bead = 78.30 ÷ 9 = 8.70 --- (4)
Cost of 1 marble and 1 bead = $8.70
(b)
(4)
x 4 4 marbles + 4 beads = 4 x 8.70 = 34.80 --- (5)
(2) - (5)
5 marbles + 4 beads - 4 marbles - 4 beads = 36.40 - 34.80
5 marbles - 4 marbles - 4 beads + 4 beads = 1.60
1 marble = 1.60
Cost of 1 marble = $1.60
(c)
Substitute 1 marble = 1.60 into (4).
1 marble + 1 bead = 8.70
1.60 + 1 bead = 8.70
1 bead = 8.70 - 1.60 = 7.10
Cost of 1 bead = $7.10
Answer(s): (a) $8.70; (b) $1.60; (c) $7.10