15. Сократите дроби: 6/12, 35/42, 6/60, 22/55, 8/10, 150/400, 12/16, 12/144, 58/377; 7/49, 16/28, 14/91, 18/54, 52/65, 600/850, 20/30, 144/216, 57/342; 36/96, 18/81, 24/30, 9/24, 8/14, 23/115, 50/75, 56/126, 15/1656; 5/55, 32/48, 10/15, 10/22, 20/30, 126/840, 4/4, 78/390, 88/484.

Делим числитель и знаменатель каждой дроби на их общий наибольший делитель.

\(\frac{6}{12}=\frac{1}{2};\ \frac{35}{42}=\frac{5}{6};\ \frac{6}{60}=\frac{1}{10};\ \frac{22}{55}=\frac{2}{5};\ \frac{8}{10}=\frac{4}{5}\).

\(\frac{150}{400}=\frac{3}{8};\ \frac{12}{16}=\frac{3}{4};\ \frac{12}{144}=\frac{1}{12};\ \frac{58}{377}=\frac{2}{13}\).

\(\frac{7}{49}=\frac{1}{7};\ \frac{16}{28}=\frac{4}{7};\ \frac{14}{91}=\frac{2}{13};\ \frac{18}{54}=\frac{1}{3};\ \frac{52}{65}=\frac{4}{5}\).

\(\frac{600}{850}=\frac{12}{17};\ \frac{20}{30}=\frac{2}{3};\ \frac{144}{216}=\frac{2}{3};\ \frac{57}{342}=\frac{1}{6}\).

\(\frac{36}{96}=\frac{3}{8};\ \frac{18}{81}=\frac{2}{9};\ \frac{24}{30}=\frac{4}{5};\ \frac{9}{24}=\frac{3}{8};\ \frac{8}{14}=\frac{4}{7}\).

\(\frac{23}{115}=\frac{1}{5};\ \frac{50}{75}=\frac{2}{3};\ \frac{56}{126}=\frac{4}{9};\ \frac{15}{1656}=\frac{5}{552}\).

\(\frac{5}{55}=\frac{1}{11};\ \frac{32}{48}=\frac{2}{3};\ \frac{10}{15}=\frac{2}{3};\ \frac{10}{22}=\frac{5}{11};\ \frac{20}{30}=\frac{2}{3}\).

\(\frac{126}{840}=\frac{3}{20};\ \frac{4}{4}=1;\ \frac{78}{390}=\frac{1}{5};\ \frac{88}{484}=\frac{2}{11}\).

Ответ: в порядке, указанном в условии:
1/2, 5/6, 1/10, 2/5, 4/5, 3/8, 3/4, 1/12, 2/13;
1/7, 4/7, 2/13, 1/3, 4/5, 12/17, 2/3, 2/3, 1/6;
3/8, 2/9, 4/5, 3/8, 4/7, 1/5, 2/3, 4/9, 5/552;
1/11, 2/3, 2/3, 5/11, 2/3, 3/20, 1, 1/5, 2/11.