Select the correct answer.
 Rick is driving to his uncle's house in Greensville, which is 120 miles from Rick's town. After covering x miles, Rick sees a sign stating that Greensville is 20 miles away. Which equation, when solved, will give the value of x?
 A. 
 x + 120 = 20 
 B. 
 x × 120 = 20
 C. 
 x + 20 = 120
 D. 
 x × 20 = 120