Помогите пожалуйста решить

1)
$\frac{18}{57} = \frac{6 \times 3}{19 \times 3} = \frac{6}{19}$
$\frac{13}{39} = \frac{13}{13 \times 3} = \frac{1}{3}$
$\frac{81}{270} = \frac{27 \times 3}{27 \times 10} = \frac{3}{10}$
2)
$\frac{7}{3} + \frac{7}{8} = \frac{7 \times 8}{24} + \frac{7 \times 3}{24} = \frac{56}{24} + \frac{21}{24} = \frac{77}{24}$
3)
$\frac{5}{18} - \frac{11}{60} = \frac{5 \times 10}{180} - \frac{11 \times 3}{180} = \frac{50}{180} - \frac{33}{180} = \frac{17}{180}$
4)
$\frac{4}{7} + \frac{2}{21} = \frac{4 \times 3}{21} + \frac{2}{21} = \frac{12}{21} + \frac{2}{21} = \frac{14}{21} = \frac{2}{3}$
5)
$\frac{49}{75} \: \: \frac{2}{3} \\ \frac{49}{75} \: \: \frac{2 \times 25}{75} \\ \frac{49}{75} < \frac{50}{75}$
6)
$\frac{1}{7} + \frac{2}{35} - \frac{1}{5} = \frac{5}{35} + \frac{2}{35} - \frac{7}{35} = \frac{5 + 2 - 7}{35} = \frac{1}{35}$