How does drawing a rectangle support the idea of composing a larger unit from smaller units

When you think rectangles, you think areas. Small areas aggregate to form bigger ones.

If you drew a rectangle, it's easy to divide it into smaller units by simply taking a line through its midsection from one length to the other and one width to the other. One can either form smaller squares or rectangles from a larger one.

When that is one, you'd have taken the larger area of a rectangle which is simply the product of the value of its length and it's the breadth, and divided it into smaller units.

Cheers!

a = 11 : 4

b = 38

c = 1 for every 6

it would open into a square depending on the type of envelope i’m not sure about the second part