Adam pays $12.90 for 3 beads and 2 stickers.
A bead costs $3.80 more than 1 sticker.
What is the cost of 2 beads and 3 stickers?
Choose the cheaper item to be 1 u.
1 bead costs $3.80 more than 1 sticker.
The cheaper item is the sticker.

Cost of the sticker = 1 u
Cost of the bead = 1 u + 3.80

Cost of 3 beads = 3 x (1 u + 3.80) = 3 u + 11.40
Cost of 2 stickers = 2 u

Total cost of 3 beads and 2 stickers
= 3 u + 11.40 + 2 u
= 3 u + 2 u + 11.40
= 5 u + 11.40

5 u + 11.40 = 12.90
5 u = 12.90 - 11.40
5 u = 1.50

1 u = 1.50 ÷ 5 = 0.30

Cost of 2 beads and 3 stickers
= 2 x (1 u + 3.80) + 3 u
= 2 u + 7.60 + 3 u
= 2 u + 3 u + 7.60
= 5 u + 7.60
= 5 x 0.30 + 7.60
= 1.50 + 7.60
= $9.10

Answer(s): $9.10