Atruck travels at the rate of 80 kilometers per hour. how much distance will it travel in 30 minutes?

The truck cover 80 km per 1 hour that is 80 km per 60 min.

For half the time, the truck will cover half the distance.

So, for 30 min (half of 60 min) the truck will travel 40 km (half of 80).

In general, we could have done the following:

The truck travels

80 km per 60 min, so:

80/60  km per 60/60 min

that is

4/3 km per 1 minute.

in 30 minutes, the truck will cover a distance of (4/3)*30=4*10=40 (min)

40 min