Julien can swim at 40 yards per minute what is his speed in feet per hour

So if there is 3 feet in 1 yard, you do number of yard times 3

3fx40y=120f so Julien can swim 120 feet in 1 minute

but we want to know how many feet / hour right?

so how many minutes are in an hour? 60 minutes, and he can swim 120 feet in 1 minute

so you do 120f x 60m = 7,200 and that should be the number of feet per hour ...