To be able to answer this question, you must recall the facts about speed/time graphs:- A straight, horizontal line means there is no change in speed- A straight, vertical line means that there is an instantaneous change in speed- A curved line means that there is a change of speed at an inconsistent rate over time- A straight diagonal line means that there is a change of speed at a consistent rate over time- The relationship between speed and time is defined: distance = speed x timeUsing these facts we can answer the questions:a) A constant deceleration would be represented by a straight diagonal line sloping downwards. The diagonal represents a change in speed and the fact it is straight shows that the change is constant.b) We know the relationship between the three variables is distance = speed x time. On the graph, the distance is represented by the area confined by the line of the graph and the two axis or what is commonly refered to as 'the area under the graph'.