Answer :
12 servings
Explanation
you can easily solve this by using a rule of three
Step 1
Gary is making a casserole( 4 servings) but only needs 1/3 of the
original serving size,then
[tex]\begin{gathered} if\text{Gary} \\ \frac{1}{3}\text{ of the original serving size}\rightarrow4\text{ serving } \\ \text{the relation is} \\ \frac{\frac{1}{3}}{\frac{4}{1}}=\frac{1}{12} \end{gathered}[/tex]Step 2
Let
x represents the number of servings in the original recipe(1),then
[tex]\begin{gathered} 1\rightarrow x \\ \text{the relation is the same, so} \\ \frac{1}{x}=\frac{1}{12} \end{gathered}[/tex]Step 3
solve for x
[tex]\begin{gathered} \frac{1}{x}=\frac{1}{12} \\ 12\cdot1=1\cdot x \\ x=12 \end{gathered}[/tex]the original recipe made 12 servings