The window shown here is a composite of a rectangle and a semicircle. If each square of the grid is six inches by six inches, what is the perimeter of the rectangular part of the window, ABCD? Include only the outside perimeter.

So break it up into 2 parts.

The bottom rectangle:
The length from A to D is 8 blocks, which is the same as the length from BC.
The length of D to C is 6 blocks.

So the length from A to D to C to B is 8 blocks + 6 blocks + 8 blocks = 22 blocks

The top circle:
Find the circumference of the circle using C = pi * diameter
The diameter is 6 blocks, so the circumference is:
C = pi * 6
you only have half of the circle so you must divide that by 2, so its:
pi * 6 / 2 = pi * 3

Add those 2 parts together and your total perimeter is:
22 blocks + pi * 3 blocks

calculate that then multiply that by 6, since each block is 6 inches