There are 4 cups of oatmeal for 5 cups of milk and 8 cups of oatmeal for 10 cups of milk and 12 cups of oatmeal for 15 cups of milk. How many cups of oatmeal used for 1 cup of milk?

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.