427. Есептеңдер: 1) 2/3 + (−10 1/3); 2) −3/8 + 4/7; 3) 3/5 + (−1 5/6); 4) 2/9 + (−1 5/6); 5) 4/5 + (−2/7); 6) −9 + 2/9.

1. \(\frac{2}{3}+(-10\frac{1}{3})=\frac{2}{3}-\frac{31}{3}=-\frac{29}{3}=-9\frac{2}{3}\).
2. \(-\frac{3}{8}+\frac{4}{7}=\frac{-21+32}{56}=\frac{11}{56}\).
3. \(\frac{3}{5}+(-1\frac{5}{6})=\frac{18}{30}-\frac{55}{30}=-\frac{37}{30}=-1\frac{7}{30}\).
4. \(\frac{2}{9}+(-1\frac{5}{6})=\frac{4}{18}-\frac{33}{18}=-\frac{29}{18}=-1\frac{11}{18}\).
5. \(\frac{4}{5}-\frac{2}{7}=\frac{28-10}{35}=\frac{18}{35}\).
6. \(-9+\frac{2}{9}=-\frac{81}{9}+\frac{2}{9}=-\frac{79}{9}=-8\frac{7}{9}\).

Жауабы: 1) −9 2/3; 2) 11/56; 3) −1 7/30; 4) −1 11/18; 5) 18/35; 6) −8 7/9.