She needs 3 3/4 cups more
Explanation:
(I think you accidently put the 18 3/4 part twice) but anyways if you add 3/4 and 1/2 you get 1 and 1/4 that will be important later then you do 18 + 6 = 24 and then add your 1 and 1/4 to get a total of 25 1/4 then you just minus that from 29 and get 3 and 3/4
Hope this Helps!