Question 123635
Let the speed of the car be "X".  From 3 am until 1 pm (10 hours), the car will travel 10*X miles.  

The speed of the airplane is (X +200).  From 11 am until 1 pm (2 hours), the plane will travel 2*(X+200).

The distance travelled is the same, so:

10*X = 2*(x+200)= 2x+400

Subtract 2*X from both sides:

8*X = 400
X = 400/8 = 50 mph.