Adam pays $8.70 for 3 stickers and 2 beads.
A sticker costs $1.40 more than 1 bead.
What is the cost of 2 stickers and 4 beads?
Choose the cheaper item to be 1 u.
1 sticker costs $1.40 more than 1 bead.
The cheaper item is the bead.

Cost of the bead = 1 u
Cost of the sticker = 1 u + 1.40

Cost of 3 stickers = 3 x (1 u + 1.40) = 3 u + 4.20
Cost of 2 beads = 2 u

Total cost of 3 stickers and 2 beads
= 3 u + 4.20 + 2 u
= 3 u + 2 u + 4.20
= 5 u + 4.20

5 u + 4.20 = 8.70
5 u = 8.70 - 4.20
5 u = 4.50

1 u = 4.50 ÷ 5 = 0.90

Cost of 2 stickers and 4 beads
= 2 x (1 u + 1.40) + 4 u
= 2 u + 2.80 + 4 u
= 2 u + 4 u + 2.80
= 6 u + 2.80
= 6 x 0.90 + 2.80
= 5.40 + 2.80
= $8.20

Answer(s): $8.20