If Adam buys 3 marbles and 4 beads, it costs $45.50.
If Adam buys 4 marbles and 3 beads, he will have $1.40 left.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
(a)
3 marbles + 4 beads = 45.50 --- (1)
4 marbles + 3 beads = 45.50 - 1.40 = 44.10 --- (2)
(1) + (2)
7 marbles + 7 beads = 89.60 --- (3)
(3)
÷ 7 1 marble + 1 bead = 89.60 ÷ 7 = 12.80 --- (4)
Cost of 1 marble and 1 bead = $12.80
(b)
(4)
x 3 3 marbles + 3 beads = 3 x 12.80 = 38.40 --- (5)
(2) - (5)
4 marbles + 3 beads - 3 marbles - 3 beads = 44.10 - 38.40
4 marbles - 3 marbles - 3 beads + 3 beads = 5.70
1 marble = 5.70
Cost of 1 marble = $5.70
(c)
Substitute 1 marble = 5.70 into (4).
1 marble + 1 bead = 12.80
5.70 + 1 bead = 12.80
1 bead = 12.80 - 5.70 = 7.10
Cost of 1 bead = $7.10
Answer(s): (a) $12.80; (b) $5.70; (c) $7.10