Julia needs 3 

 cups of oatmeal, and she can only get it in 

 cup quantities at a time. We know that 

 makes 1 whole, so we need to multiply the amount of whole cups she has by 4.
3 * 4 = 12
Finally, we see that there is 

 cup of extra oatmeal that Julia wants, so we add one more to our sum.
It will take 13 sets of 

 cups of oatmeal to make 3 

 cups of oatmeal.
Hope that helped =)