If Adam buys 3 marbles and 4 beads, it costs $50.30.
If Adam buys 4 marbles and 3 beads, he will have $4.70 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 = 50.30 --- (1)
4 marbles + 3 beads = 50.30 - 4.70 = 45.60 --- (2)
(1) + (2)
7 marbles + 7 beads = 95.90 --- (3)
(3)
÷ 7 1 marble + 1 bead = 95.90 ÷ 7 = 13.70 --- (4)
Cost of 1 marble and 1 bead = $13.70
(b)
(4)
x 3 3 marbles + 3 beads = 3 x 13.70 = 41.10 --- (5)
(2) - (5)
4 marbles + 3 beads - 3 marbles - 3 beads = 45.60 - 41.10
4 marbles - 3 marbles - 3 beads + 3 beads = 4.50
1 marble = 4.50
Cost of 1 marble = $4.50
(c)
Substitute 1 marble = 4.50 into (4).
1 marble + 1 bead = 13.70
4.50 + 1 bead = 13.70
1 bead = 13.70 - 4.50 = 9.20
Cost of 1 bead = $9.20
Answer(s): (a) $13.70; (b) $4.50; (c) $9.20