Сделай те плз,даю 100балов!!!

Решите задачу:

$1)64.283 + 18.977 = 83.26 \\ 2)1.2768 \div 4.2 = \frac{12768}{10000} \div \frac{42}{10} = \frac{12768}{10000} \times \frac{10}{42} = \frac{304}{1000} = 0.304 \\ 3) \frac{9}{20} - \frac{1}{5} = \frac{9 - 4}{20} = \frac{5}{20} = \frac{1}{4} = 0.25 \\ 4)6 \frac{2}{3} \times 1.8 = \frac{20}{3} \times \frac{18}{10} = \frac{12}{1} = 12 \\ 5) - 243 + 57 = - 186 \\ 6) - 8.2 + \frac{6 - 2 \frac{3}{4} }{ \frac{3}{8} } = - 8.2 + \frac{6 - \frac{11}{4} }{ \frac{3}{8} } = - 8.2 + \frac{ \frac{24 - 11}{4} }{ \frac{3}{8} } = - 8.2 + \frac{ \frac{13}{4} }{ \frac{3}{8} } = -8.2 + \frac{13}{4} \times \frac{8}{3} = - 8.2 + \frac{26}{3} = - \frac{ - 82}{10} + \frac{26}{3} = \frac{ - 246 + 260}{30} = \frac{14}{30} = \frac{7}{15}$