3 marbles and 1 bead cost $8.80.
1 marble and 3 beads cost $6.40.
- 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 6 marbles and 6 beads.
(a)
3 marbles + 1 bead = 8.80 --- (1)
1 marble + 3 beads = 6.40 --- (2)
(1) + (2)
4 marbles + 4 beads = 8.80 + 6.40
4 marbles + 4 beads = 15.20 --- (3)
(3)
÷ 44 marbles + 4 beads = 15.20
1 marble + 1 bead = 15.20 ÷ 4
1 marble + 1 bead = 3.80 --- (4)
(b)
(2) - (4)
(1 marble + 3 beads) - (1 marble + 1 marble) = 6.40 - 3.80
1 marble - 1 marble + 3 beads - 1 bead = 2.60
2 beads = 2.60
1 bead = 2.60 ÷ 2 = 1.30
Cost of 1 bead = $1.30
(c)
Substitute 1 bead = 1.30 into (4).
1 marble + 1 bead = 3.80
1 marble + 1.30 = 3.80
1 marble = 3.80 - 1.30 = 2.50
Cost of 1 marble = $2.50
(d)
(4)
x 6 1 marble + 1 bead = 3.80
6 x (1 marble + 1 marble) = 6 x 3.80
6 marbles + 6 beads = 22.80
Cost of 6 marbles and 6 beads = $22.80
Answer(s): (a) $3.80; (b) $1.30; (c) $2.50; (d) $22.80