Acar whose acceleration is constant reaches a speed of
80 km/h in 20 s starting from rest. how much more time
is required for it to reach a speed of 130 km/h?

  12.5 s

Step-by-step explanation:

If acceleration is constant, speed is proportional to time. To increase the speed by 50 km/h, the car will need an additional time given by ...

  t/(50 km/h) = (20 s)/(80 km/h)

  t = (20 s)(50/80) . . . . . multiply by 50 km/h

  t = 12.5 s

It will take 12.5 more seconds for it to reach a speed of 130 km/h.