1. Вычислите: 1) $\frac{3}{7}+\frac{4}{9}$; 2) $\frac{9}{8}-\frac{3}{8}$; 3) $\frac{13}{15}-\frac{2}{3}$; 4) $\frac{20}{21}+\frac{3}{7}$; 5) $\frac{17}{18}-\frac{11}{12}$; 6) $\frac{7}{16}+\frac{1}{6}$; 7) $\frac{2}{9}+\frac{5}{6}$; 8) $\frac{10}{21}+\frac{9}{14}$; 9) $\frac{7}{9}-\frac{4}{15}$.

Question

Вопрос: $Фото задания: 1. Вычислите: 1) $\frac{3}{7}+\frac{4}{9}$; 2) $\frac{9}{8}-\frac{3}{8}$; 3) $\frac{13}{15}-\frac{2}{3}$; 4)…$ Фото задания

Accepted Answer

$\frac{3}{7}+\frac{4}{9}=\frac{27}{63}+\frac{28}{63}=\frac{55}{63}$.
$\frac{9}{8}-\frac{3}{8}=\frac{6}{8}=\frac{3}{4}$.
$\frac{13}{15}-\frac{2}{3}=\frac{13}{15}-\frac{10}{15}=\frac{1}{5}$.
$\frac{20}{21}+\frac{3}{7}=\frac{20}{21}+\frac{9}{21}=\frac{29}{21}=1\frac{8}{21}$.
$\frac{17}{18}-\frac{11}{12}=\frac{34}{36}-\frac{33}{36}=\frac{1}{36}$.
$\frac{7}{16}+\frac{1}{6}=\frac{21}{48}+\frac{8}{48}=\frac{29}{48}$.
$\frac{2}{9}+\frac{5}{6}=\frac{4}{18}+\frac{15}{18}=\frac{19}{18}=1\frac{1}{18}$.
$\frac{10}{21}+\frac{9}{14}=\frac{20}{42}+\frac{27}{42}=\frac{47}{42}=1\frac{5}{42}$.
$\frac{7}{9}-\frac{4}{15}=\frac{35}{45}-\frac{12}{45}=\frac{23}{45}$.

Ответ: