Answer:
15 days
Step-by-step explanation:
You have 5 cups of food, and you give him 1/3 a day.
So, 5 divided by 1/3, which would get you 15 days. Or you could cross-multiply, meaning you multiply across, but in this case I just made them line up so you can see how to do it.[tex](food)/(cupsperday) = 5/\frac{1}{3} \\OR\\\frac{(food)}{1}*(cupsperday) = \frac{5}{1} *\frac{3}{1}[/tex]