## Geometry: Common Core (15th Edition)

$\frac{2}{3}$
To simplify a ratio, we divide by a fraction that is equal to $1$ (a fraction with the same number in the numerator and denominator is equal to $1$). In this case, we use $\frac{12}{12}$: $$\frac{24}{36}\div\frac{12}{12}=\frac{2}{3}$$