It says that the recipe for 9 servings would require 3/4 cup milk.
He wants to prepare recipe for 6 servings. Let's assume it requires X cups milk.
Now we can use concept of proportions to solve this problem.
The proportion of X cups for 6 servings would be same as 3/4 cup milk for 9 servings. Mathematically, we can write it as follows :-
[tex] \frac{X \;cups \;milk}{6 \;servings} = \frac{\frac{3}{4} \;cups \;milk}{9 \;servings} \\\\
Or\; \frac{X \;cups \;milk}{\frac{3}{4} \;cups \;milk} = \frac{6 \;servings}{9 \;servings} \\\\
\frac{X }{\frac{3}{4} } = \frac{6 }{9 } \\\\
X = \frac{6}{9}*\frac{3}{4} \\\\
X = \frac{6*3}{9*4} \\\\
X = \frac{18}{36} \\\\
X = \frac{1}{2} \;cup \;milk [/tex]
Hence, we require [tex] \frac{1}{2} [/tex] cup milk for 6 servings.
