First, make sure both fractions have the same denominator and neither are mixed numbers. 2 and 3/4 must be converted to an improper fraction before solving. 2 = 2/1 = 4/2 = 8/4 8/4 + 3/4 = 11/4 So 2 and 3/4 = 11/4 quarts. 1/2 quart must have the same denominator as 11/4. 1/2 = 2/4. To find how much more broth you need, subtract 2/4 from 11/4. 11/4 - 2/4 = 9/4 So you need 9/4 quarts more broth to make the soup. As a mixed number, this is 2 and 1/4 quarts more.