Astroke in the primary motor area has caused don to lose control over his skeletal muscles on the right side of his body. what lobe of his brain was damaged:

A stroke is a kind of vascular brain injury ischemic in origin meaning there is decreased blood flow in one or more parts of the brain, most commonly caused by narrowing of arteries. The primary motor area is located in the frontal lobe, specifically the precentral gyrus or Brodmann area 4. Since the patient has lost motor activity on his right side of the body, then the more specific answer is the stroke is located in the left (contralateral because of decussation) frontal lobe, precentral gyrus. 

The answer is constant.