1. Вычислите: 1)17\18-7\18+5\18; 2)3 4\19-1 2\19+5 10\19 2. Выполните действия: а) 4\5 : 7; б)13\51  3.

1)[latex] \frac{17}{18} - \frac{7}{18} + \frac{5}{18} = \frac{10+5}{18} = \frac{15}{18} = \frac{5}{6} [/latex] 2)[latex]3 \frac{4}{19} -1 \frac{2}{19}+5 \frac{10}{19} = \frac{61}{19} - \frac{21}{19} + \frac{105}{19} = \frac{40}{19} + \frac{105}{19} = \frac{145}{19} =7 \frac{12}{19} [/latex] а)[latex] \frac{4}{5} :7= \frac{4}{5} * \frac{1}{7} = \frac{4}{35} [/latex] б)[latex] \frac{13}{51} : 3= \frac{13}{51} * \frac{1}{3} = \frac{13}{153} [/latex] б2)[latex] \frac{13}{51} * 3= \frac{39}{51} = \frac{13}{17} [/latex]