While baking, evan discovered a recipe that required 1/2 cup of walnuts for every 2 1/4 cups of flour. how many cups of walnuts will he need for 4 cups of flour

9/4 cups of flour is equal to 2 1/4
2/4 cups of flour is equal to 1/2
SO
16/4 cup flour is equal to 4
Which is 7/4 cups more than 2 1/4
7/4 cups is 1 3/4 cups (1/2 a cups less than 2 1/4)
Which means he needs 1 3/4 cups of walnuts.
Simplfied- 4 cups is 1/2 a cups short of double, since the flour is done is quarters, take the 1/4 cup away from the walnuts.(times 1/2 by 1/2 you get 1/4 subtract it)

The answer would be -3.9> -4.5