Answer
$\frac{2\frac{1}{4}}{24} = \frac{6\frac{3}{4}}{72}$ or $\frac{\frac{9}{4}}{24}=\frac{\frac{27}{4}}{72}$
Work Step by Step
x is to y is the same as $\frac{x}{y}$
So $2\frac{1}{4}$ cups of flour is to 24 cookies as $6\frac{3}{4}$ cups of flour is to 72 cookies is the same as $\frac{2\frac{1}{4}}{24} = \frac{6\frac{3}{4}}{72}$ or $\frac{\frac{9}{4}}{24}=\frac{\frac{27}{4}}{72}$