Adam pays $6.70 for 2 stickers and 3 beads.
A sticker costs $3.10 more than 1 bead.
What is the cost of 3 stickers and 2 beads?
Choose the cheaper item to be 1 u.
1 sticker costs $3.10 more than 1 bead.
The cheaper item is the bead.

Cost of the bead = 1 u
Cost of the sticker = 1 u + 3.10

Cost of 2 stickers = 2 x (1 u + 3.10) = 2 u + 6.20
Cost of 3 beads = 3 u

Total cost of 2 stickers and 3 beads
= 2 u + 6.20 + 3 u
= 2 u + 3 u + 6.20
= 5 u + 6.20

5 u + 6.20 = 6.70
5 u = 6.70 - 6.20
5 u = 0.50

1 u = 0.50 ÷ 5 = 0.10

Cost of 3 stickers and 2 beads
= 3 x (1 u + 3.10) + 2 u
= 3 u + 9.30 + 2 u
= 3 u + 2 u + 9.30
= 5 u + 9.30
= 5 x 0.10 + 9.30
= 0.50 + 9.30
= $9.80

Answer(s): $9.80