Let’s write the first case as a fraction to show the dollars per hour.
52 dollars/4 hours
When we reduce that we get 13 dollars/hour.
You can do the same thing for the second scenario and you make the same amount per hour.
Now let’s find our answer by dividing 39 by 13.
39/13=3
So you would have to work for 3 hours to make 39 dollars