If Adam buys 3 beads and 4 marbles, it costs $33.50.
If Adam buys 4 beads and 3 marbles, he will have $4.70 left.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 bead.
- Find the cost of 1 marble.
(a)
3 beads + 4 marbles = 33.50 --- (1)
4 beads + 3 marbles = 33.50 - 4.70 = 28.80 --- (2)
(1) + (2)
7 beads + 7 marbles = 62.30 --- (3)
(3)
÷ 7 1 bead + 1 marble = 62.30 ÷ 7 = 8.90 --- (4)
Cost of 1 bead and 1 marble = $8.90
(b)
(4)
x 3 3 beads + 3 marbles = 3 x 8.90 = 26.70 --- (5)
(2) - (5)
4 beads + 3 marbles - 3 beads - 3 marbles = 28.80 - 26.70
4 beads - 3 beads - 3 marbles + 3 marbles = 2.10
1 bead = 2.10
Cost of 1 bead = $2.10
(c)
Substitute 1 bead = 2.10 into (4).
1 bead + 1 marble = 8.90
2.10 + 1 marble = 8.90
1 marble = 8.90 - 2.10 = 6.80
Cost of 1 marble = $6.80
Answer(s): (a) $8.90; (b) $2.10; (c) $6.80