Ijust need the letter on all of these

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

The amount spent on food and drink by 20 customers is shown below what is the modal amount spent ?

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex