3 marbles and 1 bead cost $14.60.
1 marble and 3 beads cost $15.80.
- 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)
3 marbles + 1 bead = 14.60 --- (1)
1 marble + 3 beads = 15.80 --- (2)
(1) + (2)
4 marbles + 4 beads = 14.60 + 15.80
4 marbles + 4 beads = 30.40 --- (3)
(3)
÷ 44 marbles + 4 beads = 30.40
1 marble + 1 bead = 30.40 ÷ 4
1 marble + 1 bead = 7.60 --- (4)
(b)
(2) - (4)
(1 marble + 3 beads) - (1 marble + 1 marble) = 15.80 - 7.60
1 marble - 1 marble + 3 beads - 1 bead = 8.20
2 beads = 8.20
1 bead = 8.20 ÷ 2 = 4.10
Cost of 1 bead = $4.10
(c)
Substitute 1 bead = 4.10 into (4).
1 marble + 1 bead = 7.60
1 marble + 4.10 = 7.60
1 marble = 7.60 - 4.10 = 3.50
Cost of 1 marble = $3.50
(d)
(4)
x 8 1 marble + 1 bead = 7.60
8 x (1 marble + 1 marble) = 8 x 7.60
8 marbles + 8 beads = 60.80
Cost of 8 marbles and 8 beads = $60.80
Answer(s): (a) $7.60; (b) $4.10; (c) $3.50; (d) $60.80