If Adam buys 3 marbles and 4 beads, it costs $35.20.
If Adam buys 4 marbles and 3 beads, he will have $6.70 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 = 35.20 --- (1)
4 marbles + 3 beads = 35.20 - 6.70 = 28.50 --- (2)
(1) + (2)
7 marbles + 7 beads = 63.70 --- (3)
(3)
÷ 7 1 marble + 1 bead = 63.70 ÷ 7 = 9.10 --- (4)
Cost of 1 marble and 1 bead = $9.10
(b)
(4)
x 3 3 marbles + 3 beads = 3 x 9.10 = 27.30 --- (5)
(2) - (5)
4 marbles + 3 beads - 3 marbles - 3 beads = 28.50 - 27.30
4 marbles - 3 marbles - 3 beads + 3 beads = 1.20
1 marble = 1.20
Cost of 1 marble = $1.20
(c)
Substitute 1 marble = 1.20 into (4).
1 marble + 1 bead = 9.10
1.20 + 1 bead = 9.10
1 bead = 9.10 - 1.20 = 7.90
Cost of 1 bead = $7.90
Answer(s): (a) $9.10; (b) $1.20; (c) $7.90