1) 2 1/5 + 6/4 =

Задание первое 1) $2 \frac{1}{5} + \frac{6}{4} = 2 + \frac{4}{20} + \frac{30}{20} = 2 + \frac{34}{20} = 2 + 1 \frac{14}{20} = 3 \frac{7}{10}$ 2) $3 \frac{4}{15} + 5 \frac{10}{20} = 3 \frac{16}{60} + 5 \frac{30}{60} = 8 \frac{46}{60} = 8 \frac{23}{30}$ 3) $6 \frac{8}{10} + 2 \frac{6}{3} = 6 \frac{4}{5} + 2 + 2 = 10 \frac{4}{5}$ 4) $1 \frac{3}{8} + 2 \frac{1}{9} = 1 \frac{27}{72} + 2 \frac{8}{72} = 3 \frac{35}{72}$ Задание второе 1) $7 \frac{2}{4} - \frac{5}{3} = 7 \frac{6}{12} - \frac{20}{12} = 6 \frac{18}{12} - \frac{20}{12} = 6 - \frac{2}{12} = 5 \frac{10}{12} = 5 \frac{5}{6}$ 2) $2 \frac{10}{5} - 1 \frac{4}{10} = 2 + 2 - 1 \frac{2}{5} = 4 - 1 \frac{2}{5} = 2 \frac{3}{5}$ 3) $8 \frac{2}{20} - 2 \frac{8}{15} = 8 \frac{6}{60} - 2 \frac{32}{60} = 7 \frac{66}{60} - 2 \frac{32}{60} = 5 \frac{34}{60} = 5 \frac{17}{30}$ 4) $\frac{6}{2} - 1 = 3 - 1 = 2$ Задание третье 1) $2 \frac{4}{3} \cdot 1 \frac{6}{8} = (2 + 1 \frac{1}{3}) \cdot 1 \frac{3}{4} = 3 \frac{1}{3} \cdot 1 \frac{3}{4} = \frac{10}{3} \cdot \frac{7}{4} = \frac{70}{12} = \frac{35}{6} = 5 \frac{5}{6}$ 2) $2 \frac{4}{8} \cdot 3 \frac{4}{10} = 2 \frac{1}{2} \cdot 3 \frac{2}{5} = \frac{5}{2} \cdot \frac{17}{5} = \frac{17}{2} = 8 \frac{1}{2}$ 3) $5 \frac{6}{2} \cdot 8 = 8 \cdot 8 = 64$ 4) $1 \frac{3}{8} \cdot 2 \frac{3}{8} = \frac{11}{8} \cdot \frac{19}{8} = \frac{209}{64} = 3 \frac{17}{64}$ Задание четвертое 1) $\frac{2}{5} : 2 = \frac{2}{5} \cdot \frac{1}{2} = \frac{1}{5}$ 2) $2 \frac{4}{15} : 4 \frac{15}{20} = \frac{34}{15} : \frac{95}{20} = \frac{34}{15} \cdot \frac{20}{95} = \frac{34 \cdot 4}{3 \cdot 95} = \frac{136}{285}$