Our equation for this situation is C(x) = 3x + 5, where C(x) is the total cost paid, 3 is the amount per ride x, and 5 is the cost to just walk in, rides or no rides. Our total cost is 17, so we can sub that in and solve for x. 17 = 3x+5. Subtract 5 from both sides to get 12 = 3x. Divide both sides by 3 to get x = 4. She rode 4 rides.
