284 и 285 плиииздаю 20 бал

284.
$(2 \frac{11}{13} - 18 \frac{7}{13} \div 10 \frac{1}{24} ) \div \frac{15}{62} - 2.4 = ( \frac{37}{13} - \frac{241}{13} \div \frac{241}{24} ) \div \frac{15}{62} - \frac{24}{10} = ( \frac{37}{13} - \frac{241}{13} \times \frac{24}{241} ) \times \frac{62}{15} - \frac{24}{10} = ( \frac{37}{13} - \frac{24}{13} ) \times \frac{62}{15} - \frac{24}{10} = \frac{13}{13} \times \frac{62}{15} - \frac{24}{10} = \frac{62}{15} - \frac{24}{10} = \frac{62 \times 2 - 24 \times 3}{30} = \frac{124 - 72}{30} = \frac{52}{30} = 1 \frac{22}{30}$
285.
$\frac{y}{2.8 + 8.7} = \frac{ 2\frac{3}{5} }{10 - 7.7} \\ \frac{y}{11.5} = \frac{2.6}{2.3} \\ y \times 2.3 = 11.5 \times 2.6 \\ y = \frac{29.9}{2.3} = \frac{299}{23} = 13$