1. Найдите значение суммы: a) -0,37 + (-0,84); б) -3$$\frac{7}{9}$$+(-2$$\frac{5}{9}$$); в) -$$\frac{3}{7}$$+(-$$\frac{5}{6}$$); г) -$$\frac{5}{12}$$+(-$$\frac{2}{15}$$); д) -13$$\frac{3}{14}$$+(-1$$\frac{4}{63}$$).

а) −0.37 + (−0.84) = -1.21

б) −3$$\frac{7}{9}$$+(-2$$\frac{5}{9}$$) = -3$$\frac{7}{9}$$ - 2$$\frac{5}{9}$$ = -5$$\frac{12}{9}$$ = -6$$\frac{3}{9}$$ = -6$$\frac{1}{3}$$

в) -$$\frac{3}{7}$$+(-$$\frac{5}{6}$$) = -$$\frac{3}{7}$$ - $$\frac{5}{6}$$ = $$\frac{-3 \cdot 6 - 5 \cdot 7}{42}$$ = $$\frac{-18 - 35}{42}$$ = -$$\frac{53}{42}$$ = -1$$\frac{11}{42}$$

г) -$$\frac{5}{12}$$+(-$$\frac{2}{15}$$) = -$$\frac{5}{12}$$ - $$\frac{2}{15}$$ = $$\frac{-5 \cdot 5 - 2 \cdot 4}{60}$$ = $$\frac{-25 - 8}{60}$$ = -$$\frac{33}{60}$$ = -$$\frac{11}{20}$$

д) -13$$\frac{3}{14}$$+(-1$$\frac{4}{63}$$) = -13$$\frac{3}{14}$$ - 1$$\frac{4}{63}$$ = -14 - $$\frac{3}{14}$$ - $$\frac{4}{63}$$ = -14 - $$\frac{3 \cdot 9 + 4 \cdot 2}{126}$$ = -14 - $$\frac{27 + 8}{126}$$ = -14 - $$\frac{35}{126}$$ = -14 - $$\frac{5}{18}$$ = -14$$\frac{5}{18}$$