Is there a relationship between the area and perimeter of a rectangle?

Don't think so, area has nothing to do with perimeter.

Area you multiply the length and base , but perimeter you multiply length x width x height or also know as LxWxH.  ex. area. Length = 4. height = 2. 4 x 2 = 8. your area is 8. perimeter. length = 4. width = 2 . height = 3. 4x2x3=24. your perimenter is 24.

The linear equation is: y=ax+b