Answer:
Step-by-step explanation:
The area of a square of side, [tex]s[/tex], is given by [tex]s^2[/tex]
The area of the frame with the painting is [tex]x^2[/tex].
Because there is a 5 inch border between the painting and the frame, the side length of the painting is [tex]x-5[/tex]. Hence the area of the painting is [tex](x-5)^2[/tex].
The total area of the border is the difference of the two areas:
[tex]A = x^2 - (x-5)^2[/tex]
[tex]A = x^2 - (x^2 - 10x + 25)[/tex]
[tex]A = x^2 - x^2 + 10x - 25[/tex]
[tex]A = 10x - 25[/tex]
