в) $$7\frac{24}{25} - 3\frac{12}{25} - 1\frac{7}{25} = (7-3-1) + (\frac{24}{25} - \frac{12}{25} - \frac{7}{25}) = 3 + \frac{5}{25} = 3\frac{1}{5}$$;
г) $$23\frac{15}{49} - 13\frac{19}{49} - 1\frac{30}{49} = (23-13-1) + (\frac{15}{49} - \frac{19}{49} - \frac{30}{49}) = 9 + \frac{-34}{49} = 9 - \frac{34}{49} = 8 + 1 - \frac{34}{49} = 8 + \frac{49}{49} - \frac{34}{49} = 8 + \frac{15}{49} = 8\frac{15}{49}$$