A certain car is capable of accelerating at a rate of +0.90 m/s2. How long does it take for this car to go from a speed of 55 mi/h to a speed of 80 mi/h?

Answer 1

It is mainly a matter of units conversion.
Decide on what units you'd like to use for the final answer (usually seconds for cars). Convert everything to metres and seconds and use
time = (final velocity - initial velocity) / acceleration

To change from mph to m/s
multiply by
63360*0.0254/3600
=0.44704
I get 12.4 seconds