Adam pays $17.30 for 3 stickers and 4 marbles.
A sticker costs $4.60 more than 1 marble.
What is the cost of 2 stickers and 3 marbles?
Choose the cheaper item to be 1 u.
1 sticker costs $4.60 more than 1 marble.
The cheaper item is the marble.

Cost of the marble = 1 u
Cost of the sticker = 1 u + 4.60

Cost of 3 stickers = 3 x (1 u + 4.60) = 3 u + 13.80
Cost of 4 marbles = 4 u

Total cost of 3 stickers and 4 marbles
= 3 u + 13.80 + 4 u
= 3 u + 4 u + 13.80
= 7 u + 13.80

7 u + 13.80 = 17.30
7 u = 17.30 - 13.80
7 u = 3.50

1 u = 3.50 ÷ 7 = 0.50

Cost of 2 stickers and 3 marbles
= 2 x (1 u + 4.60) + 3 u
= 2 u + 9.20 + 3 u
= 2 u + 3 u + 9.20
= 5 u + 9.20
= 5 x 0.50 + 9.20
= 2.50 + 9.20
= $11.70

Answer(s): $11.70