PLEASE HELP ME FAST I WILL GIVE BRAINLEIST

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

Hurry and answer this! circle x with a radius of 6 units and circle y with a radius of 2 units are shown which steps would prove the circles similar? translate the circles so they share a common center point, and dilate circle y by a scale factor of 4. translate the circles so the center of one circle rests on the edge of the other circle, and dilate circle y by a scale factor of 4. translate the circles so they share a common center point, and dilate circle y by a scale factor of 3. translate the circles so the center of one circle rests on the edge of the other circle, and dilate circle y by a scale factor of 3

Which of the following answers is 5/25 simplified? 1/5 5/5 2/5 1/25