Ответ:

  1. \(8\frac{9}{10}-x=4\frac{5}{6}\).

    \(x=8\frac{9}{10}-4\frac{5}{6}=\frac{89}{10}-\frac{29}{6}=\frac{267-145}{30}=\frac{122}{30}=\frac{61}{15}=4\frac{1}{15}\).

  2. \(\frac{9}{14}+\left(x-\frac{3}{7}\right)=\frac{23}{28}\).

    \(x-\frac{3}{7}=\frac{23}{28}-\frac{9}{14}=\frac{23}{28}-\frac{18}{28}=\frac{5}{28}\).

    \(x=\frac{5}{28}+\frac{3}{7}=\frac{5}{28}+\frac{12}{28}=\frac{17}{28}\).

Ответ: 1) \(x=4\frac{1}{15}\); 2) \(x=\frac{17}{28}\).