SOLVED! It was just a quadratic... I verified with making two right triangles under the parabolic bridge.
Problem:
A bridge is to be built across a waterway which is 50ft wide and is frequented by ships. The bridge design team determines that a parabolic opening underneath the bridge is the best possible option for both structure and functionality (keeping the waterway passable by ships while still being safe for vehicles to travel across). If parabolic opening touches the ground at the edges of the waterway and the maximum height of the opening is 60ft, what is the maximum height that a 20-foot wide boat could be and still pass through the opening?
