A children's roller coaster ride travels along 3,300 feet of track at an average rate of 15 miles per hour. How many seconds does the ride take to travel this length of track?

Need to do some unit conversions here. They give speed in mi/h but want time in seconds and give distance in feet. Easiest thing to do would be to convert the speed to ft/s:

15 mi/h x 5280 ft/mi x 1 h / 3600s = 22ft/s

Now solve for time:

Speed = distance / time

22ft/s = 3300ft / t

t = 3300ft / 22ft/s

t = 150s