Hi!
First we have to find their hourly rate. We do this by dividing their total over 4 hours by 4 to get over just 1 hour.
60 / 4 = 15
Now we divide their total of $210 by their hourly rate of $15 to find how many hours it would take.
210 / 15 = 14
It would take 14 hours to earn $210.
Hope this helps :)
