Please answer the question I’m so lost

Answer:
80 feet
Explanation:
The c term is the y-intercept, which is the height of the cable at the center of the bridge, or 0. So the equation is y = ax^2. Next, we know that the towers are 600 feet apart, so the maximum x value is 300 feet (half of 600 feet). At this point, the height of the cable is 80 feet.