Suppose Tommy walks from his home at (0, 0) to the mall at (0, 7), and then walks to a movie theater at (8, 7). After leaving the theater Tommy walks to the store at (8, 0) before returning home. If each grid square represents one block, how many blocks does he walk?

step-by-step explanation:

consider the parallelogram shown in the attached image.

in the parallelogram hijk, the length of hk is given as,

from the properties of parallelogram we know that the opposite sides of a parallelogram are parallel to each other and are equal in measure.

therefore, the length of the side ij must be equal to the length of the side hk and that is .

hence, the expression for the length of ij confirms that hijk is a parallelogram.