Level 3 Which expression shows this problem.

Mrs. Sheffield has 20 cups of flour. She uses 3 1/2 cups to make cookies and 5 3/4 cups to make pancakes.
How many cups of flour does Mrs. Sheffield have left?

20 - (3 1/2 + 5 3/4)
20 + (3 1/2 - 5 3/4)
5 3/4 - 3 1/2 - 20

Solve the problem in #1.
Only write your final answer (do not explain how you solved)