The fastest car in the world can travel at a speed of over 250 miles every hour. This is about 4 times as fast as an average highway speed of 65 miles every hour.

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm