So you can do this two ways, you can figure out how many times they move 4 feet by dividing 50 by 4, or you can figure out how many minutes it takes to move 1 ft by dividing 15 by 4.
I'm going to do 15 divided by 4 to get 1 ft every 3.75 min.
Then, you're going to multiply 3.75 by 50 to see how long it takes to move 50 ft. This gives you 187.5 minutes.
Finally, all we have to do is change minutes to hours by dividing 187.5 by 60. This gives you 3.125 hours which we can round down to 3 hours
