The diagram is the speed-time graph of the last 25 seconds of a car's journey. From t = 0 to t = 20 the car moves with a constant speed of 4 m/s. From t = 20 to t = 25 the car moves with a constant retardation.

1. (a)Calculate the retardation when t = 22.5.[1]
2. (b)Show that the distance travelled during the 25 seconds is 90 m.[1]
3. (c)On the grid below, draw the distance-time graph for the 25 seconds.[2]

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