Obliczenia
[tex](5,15-1\frac{1}{4}):2\frac{1}{6}-1=(5,15-1\frac{25}{100}):\frac{13}{6}-1=\\\\=(5,15-1,25)\cdot\frac{6}{13}-1=3,9\cdot\frac{6}{13}-1=\\\\=\frac{\not39^3}{\not10_5}\cdot\frac{\not6^3}{\not13_1}-1=\frac{9}{5}-1=\frac{9}{5}-\frac{5}{5}=\frac{4}{5}=\frac{8}{10}=\boxed{0,8}[/tex]
