Решите примеры: ж) 19/21 - 11/15; и) 11/21 + 2/26; з) 5/42 + 10/63; к) 5/24 - 7/60.

Решим данные примеры: ж) $$ \frac{19}{21} - \frac{11}{15} = \frac{19 \cdot 5}{21 \cdot 5} - \frac{11 \cdot 7}{15 \cdot 7} = \frac{95}{105} - \frac{77}{105} = \frac{95-77}{105} = \frac{18}{105} = \frac{6}{35}. $$ и) $$ \frac{11}{21} + \frac{2}{26} = \frac{11}{21} + \frac{1}{13} = \frac{11 \cdot 13}{21 \cdot 13} + \frac{1 \cdot 21}{13 \cdot 21} = \frac{143}{273} + \frac{21}{273} = \frac{143+21}{273} = \frac{164}{273}. $$ з) $$ \frac{5}{42} + \frac{10}{63} = \frac{5 \cdot 3}{42 \cdot 3} + \frac{10 \cdot 2}{63 \cdot 2} = \frac{15}{126} + \frac{20}{126} = \frac{15+20}{126} = \frac{35}{126} = \frac{5}{18}. $$ к) $$ \frac{5}{24} - \frac{7}{60} = \frac{5 \cdot 5}{24 \cdot 5} - \frac{7 \cdot 2}{60 \cdot 2} = \frac{25}{120} - \frac{14}{120} = \frac{25-14}{120} = \frac{11}{120}. $$ Ответы: ж) $$\frac{6}{35}$$; и) $$\frac{164}{273}$$; з) $$\frac{5}{18}$$; к) $$\frac{11}{120}$$.