Please please send me the answer.....

Solution :

49.
(a) 

This is the distance time graph of the car which posses non uniform speed or not constant speed.

(b) Advantages of Distance-time graph:
1) It helps us to locate the position of the object.
2) It tells us about the nature of the motion of the body- whether it is uniform or non-uniform.
3) The slope of a distance time graph gives the speed of the object.