Adam pays $11.70 for 3 beads and 2 stickers.
A bead costs $2.40 more than 1 sticker.
What is the cost of 2 beads and 4 stickers?
Choose the cheaper item to be 1 u.
1 bead costs $2.40 more than 1 sticker.
The cheaper item is the sticker.

Cost of the sticker = 1 u
Cost of the bead = 1 u + 2.40

Cost of 3 beads = 3 x (1 u + 2.40) = 3 u + 7.20
Cost of 2 stickers = 2 u

Total cost of 3 beads and 2 stickers
= 3 u + 7.20 + 2 u
= 3 u + 2 u + 7.20
= 5 u + 7.20

5 u + 7.20 = 11.70
5 u = 11.70 - 7.20
5 u = 4.50

1 u = 4.50 ÷ 5 = 0.90

Cost of 2 beads and 4 stickers
= 2 x (1 u + 2.40) + 4 u
= 2 u + 4.80 + 4 u
= 2 u + 4 u + 4.80
= 6 u + 4.80
= 6 x 0.90 + 4.80
= 5.40 + 4.80
= $10.20

Answer(s): $10.20