\( 6 \frac{2}{25} + 7 \frac{23}{25} - 4 \frac{1}{25} = (6+7-4) + \frac{2+23-1}{25} = 9 + \frac{24}{25} = 9 \frac{24}{25} \)
\( 20 \frac{1}{19} - 4 \frac{12}{19} - 5 \frac{17}{19} = (20-4-5) + \frac{1-12-17}{19} = 11 + \frac{-28}{19} = 11 - \frac{28}{19} = 11 - 1 \frac{9}{19} = 9 \frac{10}{19} \)
Ответ: а) \( 9 \frac{24}{25} \); б) \( 9 \frac{10}{19} \).