3 stickers and 1 bead cost $16.80.
1 sticker and 3 beads cost $14.40.
- Find the cost of 1 sticker and 1 bead.
- Find the cost of 1 bead.
- Find the cost of 1 sticker.
- Find the cost of 7 stickers and 7 beads.
(a)
3 stickers + 1 bead = 16.80 --- (1)
1 sticker + 3 beads = 14.40 --- (2)
(1) + (2)
4 stickers + 4 beads = 16.80 + 14.40
4 stickers + 4 beads = 31.20 --- (3)
(3)
÷ 44 stickers + 4 beads = 31.20
1 sticker + 1 bead = 31.20 ÷ 4
1 sticker + 1 bead = 7.80 --- (4)
(b)
(2) - (4)
(1 sticker + 3 beads) - (1 sticker + 1 marble) = 14.40 - 7.80
1 sticker - 1 sticker + 3 beads - 1 bead = 6.60
2 beads = 6.60
1 bead = 6.60 ÷ 2 = 3.30
Cost of 1 bead = $3.30
(c)
Substitute 1 bead = 3.30 into (4).
1 sticker + 1 bead = 7.80
1 sticker + 3.30 = 7.80
1 sticker = 7.80 - 3.30 = 4.50
Cost of 1 sticker = $4.50
(d)
(4)
x 7 1 sticker + 1 bead = 7.80
7 x (1 sticker + 1 marble) = 7 x 7.80
7 stickers + 7 beads = 54.60
Cost of 7 stickers and 7 beads = $54.60
Answer(s): (a) $7.80; (b) $3.30; (c) $4.50; (d) $54.60