Adam pays $19.10 for 4 marbles and 3 beads.
A marble costs $1.10 more than 1 bead.
What is the cost of 2 marbles and 4 beads?
Choose the cheaper item to be 1 u.
1 marble costs $1.10 more than 1 bead.
The cheaper item is the bead.

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

Cost of 4 marbles = 4 x (1 u + 1.10) = 4 u + 4.40
Cost of 3 beads = 3 u

Total cost of 4 marbles and 3 beads
= 4 u + 4.40 + 3 u
= 4 u + 3 u + 4.40
= 7 u + 4.40

7 u + 4.40 = 19.10
7 u = 19.10 - 4.40
7 u = 14.70

1 u = 14.70 ÷ 7 = 2.10

Cost of 2 marbles 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 2.10 + 2.20
= 12.60 + 2.20
= $14.80

Answer(s): $14.80