Math
posted by Jane on .
Please explain to me how to solve:
A circular mirror is surrounded by a square metal frame. The radius of the mirror is 5x. The side length of the metal frame is 15x. What is the area of the metal frame? Write your answer in factored form.

Formula for area of frame minus formula for area of mirror is the REMAINING area of frame.
Area of frame = (15x)^2.