2 marbles and 1 bead cost $11.70.
1 marble and 2 beads cost $9.60.
- Find the cost of 1 marble and 1 bead.
- Find the cost of 1 bead.
- Find the cost of 1 marble.
- Find the cost of 8 marbles and 8 beads.
(a)
2 marbles + 1 bead = 11.70 --- (1)
1 marble + 2 beads = 9.60 --- (2)
(1) + (2)
3 marbles + 3 beads = 11.70 + 9.60
3 marbles + 3 beads = 21.30 --- (3)
(3)
÷ 3
3 marbles + 3 beads = 21.30
1 marble + 1 bead = 21.30 ÷ 3
1 marble + 1 bead = 7.10 --- (4)
Cost of 1 marble and 1 bead = $7.10
(b)
(2) - (4)
(1 marble + 2 beads) - (1 marble + 1 marble) = 9.60 - 7.10
1 marble - 1 marble + 2 beads - 1 bead = 2.50
1 bead = 2.50
Cost of 1 bead = $2.50
(c)
Substitute 1 bead = 2.50 into (4).
1 marble + 1 bead = 7.10
1 marble + 2.50 = 7.10
1 marble = 7.10 - 2.50 = 4.60
Cost of 1 marble = $4.60
(d)
(4)
x 8 1 marble + 1 bead = 7.10
8 x (1 marble + 1 marble) = 8 x 7.10
8 marbles + 8 beads = 56.80
Cost of 8 marbles and 8 beads = $56.80
Answer(s): (a) $7.10; (b) $2.50; (c) $4.60; (d) $56.80