To find out how much flour is needed,we have to devided the original flour needed by 2
Hence,we get the equation:
[tex]5 \frac{1}{2} \div 2 \\ = \frac{11}{2} \times \frac{1}{2} \\ = \frac{11}{4} \\ = 2 \frac{3}{4} [/tex]
thus,he'll need 2 and 3/4 cups of flour.
hope it helps!