I WILL GIVE YOY BRAINLIEST

What is the missing constant term in the perfect square that starts with x^2 -20x

Monica build a remote control toy airplane for science project to test the plane she launched it from the top of a building the plane travel a horizontal distance of 50 feet before landing on the ground a quadratic function which models the height of the plane in feet relative to the ground at a horizontal distance of x feet from the building is shown

Complete the steps to find 4.830 ÷ 5