As I understand, you need to know the relationship between the area of similar figures. Two shapes are similar if we can turn one into the other by moving, rotating, flipping, or scaling, so this means we can make one shape bigger or smaller.
From math, if we call [tex]k[/tex] the scaling factor, then the area of one figure ([tex]A_{1}[/tex]) divided by the area of another similar figure ([tex]A_{2}[/tex]) will be equal to the scaling factor squared. In other words:
[tex]\frac{A_{1}}{A_{2}}=k^2[/tex]