Сравните пожалуйста: 6/7 & 5/6; 9/10 & 10/11; 20/21 & 21/22

Решите задачу:

$\frac{6}{7}= \frac{6*6}{7*6} = \frac{36}{42}$
$\frac{5}{6}= \frac{5*7}{6*6} = \frac{35}{42}$
$\frac{36}{42}\ \textgreater \ \frac{35}{42} , =\ \textgreater \ \frac{6}{7} \ \textgreater \ \frac{5}{6}$

$\frac{9}{10}= \frac{9*11}{10*11} = \frac{99}{110}$
$\frac{10}{11} = \frac{10*10}{11*10} = \frac{100}{110}$
$\frac{99}{110}\ \textless \ \frac{100}{110}, =\ \textgreater \ \frac{9}{10}\ \textless \ \frac{10}{11}$

$\frac{20}{21} = \frac{20*22}{21*22} = \frac{440}{462}$
$\frac{21}{22} = \frac{21*21}{22*21} = \frac{441}{462}$
$\frac{440}{462} \ \textless \ \frac{441}{462}, =\ \textgreater \ \frac{20}{21}\ \textless \ \frac{21}{22}$