speed time graph, showing acceleration then steady speed, then deceleration

The diagram shows a speed-time graph of a car.

  1. Calculate the acceleration of the car during the first \(20\) seconds.
  2. Calculate the distance the car travels from rest before it begins to decelerate.
  3. Given that the car decelerates at \(\quantity{0.5} {m/s^2}\), calculate the total time taken for the journey.