(a) the variables are the prices of the the tickets for the rides, and the total cost.
(b) y = 1.25x + 12.50
(c) 43.75 (total spent) = 1.25(cost per ticket)(25)(total spent) + b (fair admission)
1.25 times 25 = 31.25
43.75 - 31.25 = b (12.50)
y = 1.25x + 12.50