The average speed of a car is 45km/h. How far can it travel in 5 hours

The "km/h" part means "kilometres per hour", or in other words, how many kilometres it goes during 1 hour. If we have 5 hours, that means we multiplied that 1 hour by 5.

So we just multiply 45km/h by 5h and get 225km. The hours cancel out because of the fraction.

We know that avg speed times time can give us the distance. so: 45km/h*5h=225km