Сократить дробь: 2/4,5/15,25/125,13/164,16/20,8/16,10/100,100/1000, 81/90,11/121,12/144,15/75! Помогите

[latex] \frac{2}{4} = \frac{2}{2*2} = \frac{1}{2} ; \\ \frac{5}{15} = \frac{5}{5*3}= \frac{1}{3} ; \\ \frac{25}{125} = \frac{1}{5} ; \frac{16}{20}= \frac{4}{5}; \frac{8}{16}= \frac{1}{2}; \frac{10}{100}= \frac{1}{10}; \frac{100}{1000}= \frac{1}{10} ; \frac{81}{90}= \frac{9}{10}; \frac{11}{121}= \frac{1}{11}; \\ \frac{12}{144} = \frac{1}{12}; \frac{15}{75}= \frac{1}{5} [/latex] 13/164 - не сократимая