a trailer is pulling acar with a force of 900N on a level road. The car is moving at 70km/h, how much work is done by the trailer on the car in 15mm?

Answer 1

I assume you mean 15min instead of 15mm
That's 1/4 hour, so the car moves 17.5km
work = force*distance, so we have

900N * 17500m = ... J