Question

A car travels 65 km in 45 minutes what is the average speed of the car in km/h

Answer 1

So to begin your problem, you know that your car already has an average which is 65km/45 mins. The problem wants you to change this to km/hr. This means that you need to convert minutes to hours. A simple way to do this is by using fractions. 
Set your problem up with fractions similar to this:
65km/45 mins x 60 mins/1 hr.
the whole point is to cancel out your minutes, and leave the hours as your new unit for the denominator
65km/45 x 60/1 hr. 
now you want to reduce (I divided the first fraction by 5)
13km/9 x 60/1 hr.
780km/9hrs. 
That would be your answer. If someone can double check my math that would be fantastic.

Answer 2

65km in 45 min
1 hour=1h=60min
45/60=3/4
65km=3/4hour
multiply both sides by 4/3 to clear fraction
260/3=1 hour
86 2/3 =1 hour
aprox
86.666666666 km per hour