Решение:

1. а) $$rac{1}{5} + \frac{53}{50} = \frac{10}{50} + \frac{53}{50} = \frac{63}{50} = 1\frac{13}{50} = 1\frac{26}{100} = 1,26$$

2. б) $$\frac{1}{2} - \frac{2}{5} = \frac{5}{10} - \frac{4}{10} = \frac{1}{10} = 0,1$$

3. в) $$\frac{7}{6} \cdot \frac{9}{5} = \frac{7 \cdot 9}{6 \cdot 5} = \frac{7 \cdot 3}{2 \cdot 5} = \frac{21}{10} = 2,1$$

4. г) $$\frac{3}{5} : \frac{4}{35} = \frac{3}{5} \cdot \frac{35}{4} = \frac{3 \cdot 35}{5 \cdot 4} = \frac{3 \cdot 7}{1 \cdot 4} = \frac{21}{4} = 5\frac{1}{4} = 5,25$$

5. д) $$8,4 + 3,7 = 12,1$$

6. e) $$5,6 - 4,1 = 1,5$$