Uniform photo-frame border

A \(22\text{ cm}\) by \(18\text{ cm}\) frame has a uniform border of width \(x\) cm. The border area is \(144\text{ cm}^2\).

1. Give the photograph length.
2. Show that \(x^2-20x+36=0\).
3. Solve and reject the inadmissible root.
4. Find the photograph perimeter.