What is the answer to this math question 5 less than c is 47

The graph shown is the graph of which function?

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Two cars which are 40 miles apart start moving simultaneously in the same direction with constant speeds. if the speed of the car which is behind is 56 mph and the speed of the other car is 48 mph, how many hours will it take for the car which is behind to catch up the car ahead of it?