Answer:
The area of the large rectangle can be represented in two ways. Either the sum of each of the areas of the individual smaller rectangles, which is what the first equation represents, as its the base multiplied by the height (a) of each rectangle.
The second equation is a simplified version of the first one, and can be explained in three ways:
Each of the terms in the earlier equation had a common factor of a, which could be taken outside the parentheses.
or
Since the height is the same for each of the smaller rectangles, you can just multiply the height times the sum of the three smaller rectangle's widths
or
The width of the large rectangle is just the sum of each of the smaller widths, so the sum of those multiplied by a will give the area of the large rectangle.
Hope this helps!
