8)(2금+1금)-1

$$ \left( 2\frac{7}{15} + 1\frac{1}{12} \right) \cdot 1\frac{1}{9} - 1\frac{7}{8} = \left( \frac{2 \cdot 15 + 7}{15} + \frac{1 \cdot 12 + 1}{12} \right) \cdot \frac{1 \cdot 9 + 1}{9} - \frac{1 \cdot 8 + 7}{8} = \left( \frac{37}{15} + \frac{13}{12} \right) \cdot \frac{10}{9} - \frac{15}{8} = \left( \frac{37 \cdot 4}{15 \cdot 4} + \frac{13 \cdot 5}{12 \cdot 5} \right) \cdot \frac{10}{9} - \frac{15}{8} = \left( \frac{148}{60} + \frac{65}{60} \right) \cdot \frac{10}{9} - \frac{15}{8} = \frac{213}{60} \cdot \frac{10}{9} - \frac{15}{8} = \frac{213 \cdot 10}{60 \cdot 9} - \frac{15}{8} = \frac{213}{6 \cdot 9} - \frac{15}{8} = \frac{213}{54} - \frac{15}{8} = \frac{213 \cdot 4}{54 \cdot 4} - \frac{15 \cdot 27}{8 \cdot 27} = \frac{852}{216} - \frac{405}{216} = \frac{447}{216} = \frac{149}{72} = 2\frac{5}{72} $$

Ответ: $$2\frac{5}{72}$$