Решение:
\[ 4\frac{1}{4} : 2\frac{1}{2} = \frac{17}{4} : \frac{5}{2} = \frac{17}{4} \times \frac{2}{5} = \frac{17}{2} \times \frac{1}{5} = \frac{17}{10} \]
\[ 6\frac{1}{2} - \frac{17}{10} = \frac{13}{2} - \frac{17}{10} = \frac{13 \times 5}{2 \times 5} - \frac{17}{10} = \frac{65}{10} - \frac{17}{10} = \frac{48}{10} = \frac{24}{5} = 4\frac{4}{5} \]
Ответ: \[ 4\frac{4}{5} \]