If two distinct figures have the same shape they are called similar. If two figures are similar there should be a corresponding ratio between the length of each side of the figure. To find the area of similar figures determine the length ratio of height and the width of those figures. This corresponding ratio between figures is often referred to as the scale factor. The goal here is to determine the difference in the areas between two similar figures using the information provided about the lengths of their sides (formulas are provided).
Your focus on these sheets should be to determine the mixed ratios. Work the math by finding the mix that is common between the two figures and then run from there. It is always important to grasp the commonalities between each of the figures.