Nancy used 1/4 cups of oil, 1 1/4 cups of water, and 2 cups of flour as a portion of her waffle batter. how many cups did she use?

To solve this problem you must sum all the cups that Nancy used, as below:
 You have that she used 1/4 cups of oil, 1 1/4 cups of water, and 2 cups of flour. Therefore, you have:
 1/4 cups=0.25 cups
 1 1/4 cups=1.25 cups
 Then, when you sum:
 0.25 cups+1.25 cups+2 cups=3.5 cups or 7/2 cups
 Therefore, the answer is: 3.5 cups or 7/2 cups.

Answer
3 1/2 cups.

Explanation
The question requires us to add the fraction. 

1/4 +1 1/4 +2 = 1/4 + 5/4 + 2/1
                      = 1/4 + 5/4 + 8/4
                      = (1+5+8)/(4)
                      = 14/4
                      = 3 2/4
                      = 3 1/2

The means Nancy will use 3 1/2 cups.