5 beads and 1 marble cost $25.40.
1 bead and 5 marbles cost $26.20.
- Find the cost of 1 bead and 1 marble.
- Find the cost of 1 marble.
- Find the cost of 1 bead.
- Find the cost of 7 beads and 7 marbles.
(a)
5 beads + 1 marble = 25.40 --- (1)
1 bead + 5 marbles = 26.20 --- (2)
(1) + (2)
6 beads + 6 marbles = 25.40 + 26.20
6 beads + 6 marbles = 51.60 --- (3)
(3)
÷ 66 beads + 6 marbles = 51.60
1 bead + 1 marble = 51.60 ÷ 6
1 bead + 1 marble = 8.60 --- (4)
(b)
(2) - (4)
(1 bead + 5 marbles) - (1 bead + 1 marble) = 26.20 - 8.60
1 bead - 1 bead + 5 marbles - 1 marble = 17.60
4 marbles = 17.60
1 marble = 17.60 ÷ 4 = 4.40
Cost of 1 marble = $4.40
(c)
Substitute 1 marble = 4.40 into (4).
1 bead + 1 marble = 8.60
1 bead + 4.40 = 8.60
1 bead = 8.60 - 4.40 = 4.20
Cost of 1 bead = $4.20
(d)
(4)
x 7 1 bead + 1 marble = 8.60
7 x (1 bead + 1 marble) = 7 x 8.60
7 beads + 7 marbles = 60.20
Cost of 7 beads and 7 marbles = $60.20
Answer(s): (a) $8.60; (b) $4.40; (c) $4.20; (d) $60.20