First, calculate the total amount of cups of oatmeal required to make 21 batches of cookies by multiplying 21 times 2 3/4:
[tex]21\times2\frac{3}{4}=21\times2+21\times\frac{3}{4}[/tex]Simplify that fraction:
[tex]\begin{gathered} =42+\frac{21\times3}{4} \\ =42+\frac{63}{4} \\ =42+\frac{60+3}{4} \\ =42+\frac{60}{4}+\frac{3}{4} \\ =42+15+\frac{3}{4} \\ =57+\frac{3}{4} \\ =57\frac{3}{4} \end{gathered}[/tex]Since a total of 57 3/4 cups of oatmeal are needed to make 21 batches of cookies, but a package contains only 56 cups of oatmeal, therefore, there is not enough oatmeal to make 21 batches of cookies.
