Выполните сложение смешанных чисел: 1) 2 5/9 + (-1 2/3); 2) -4 2/15 + 2 1/5; 3) -1 1/3 + 4 2/21; 4) 7/11 + (-2 1/3)

**Ответ:** 1) $2 \frac{5}{9} + (-1 \frac{2}{3}) = \frac{8}{9}$ 2) $-4 \frac{2}{15} + 2 \frac{1}{5} = -1 \frac{14}{15}$ 3) $-1 \frac{1}{3} + 4 \frac{2}{21} = 2 \frac{16}{21}$ 4) $\frac{7}{11} + (-2 \frac{1}{3}) = -1 \frac{23}{33}$ **Решение:** 1) $2 \frac{5}{9} - 1 \frac{2}{3} = 2 \frac{5}{9} - 1 \frac{6}{9} = 1 \frac{14}{9} - 1 \frac{6}{9} = \frac{8}{9}$ 2) $-4 \frac{2}{15} + 2 \frac{1}{5} = -4 \frac{2}{15} + 2 \frac{3}{15} = -(4 \frac{2}{15} - 2 \frac{3}{15}) = -(3 \frac{17}{15} - 2 \frac{3}{15}) = -1 \frac{14}{15}$ 3) $-1 \frac{1}{3} + 4 \frac{2}{21} = -1 \frac{7}{21} + 4 \frac{2}{21} = 4 \frac{2}{21} - 1 \frac{7}{21} = 3 \frac{23}{21} - 1 \frac{7}{21} = 2 \frac{16}{21}$ 4) $\frac{7}{11} - 2 \frac{1}{3} = \frac{21}{33} - 2 \frac{11}{33} = -(2 \frac{11}{33} - \frac{21}{33}) = -(1 \frac{44}{33} - \frac{21}{33}) = -1 \frac{23}{33}$