The donatones drove 150 miles in 3 hours. at this rate how long will it take them to drive 400 miles?

Let's first find out how many miles they can drive in ONE hour.  150/3=50, so they drive 50 miles per hour.  So, to drive 400 miles, we need to divide the number of miles by how much they drive per hour to see how long it will take.  400/50=8, so it will take the Donatones 8 hours.

8 hours

It will take them 8 hours to drive 400 miles.