Adam pays $16.60 for 3 stickers and 4 beads.
A sticker costs $1.10 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 $1.10 more than 1 bead.
The cheaper item is the bead.

Cost of the bead = 1 u
Cost of the sticker = 1 u + 1.10

Cost of 3 stickers = 3 x (1 u + 1.10) = 3 u + 3.30
Cost of 4 beads = 4 u

Total cost of 3 stickers and 4 beads
= 3 u + 3.30 + 4 u
= 3 u + 4 u + 3.30
= 7 u + 3.30

7 u + 3.30 = 16.60
7 u = 16.60 - 3.30
7 u = 13.30

1 u = 13.30 ÷ 7 = 1.90

Cost of 2 stickers and 4 beads
= 2 x (1 u + 1.10) + 4 u
= 2 u + 2.20 + 4 u
= 2 u + 4 u + 2.20
= 6 u + 2.20
= 6 x 1.90 + 2.20
= 11.40 + 2.20
= $13.60

Answer(s): $13.60