10 баллов номер 1091

1091. 1)  5/6 * 9/15 - 5/12 * 4/15 = [latex] \frac{5}{2*3}* \frac{3*3}{3*5} - \frac{5}{3*4}* \frac{4}{3*5}= \frac{1}{2}- \frac{1}{9}= \frac{7}{18} [/latex] 2) [latex] \frac{7}{2*9}* \frac{9}{2*7}+ \frac{1}{3}* \frac{2*3}{7}= \frac{1}{4}+ \frac{2}{7}= \frac{15}{28} [/latex] 3) [latex] \frac{3*3*2}{5*4*3}+ \frac{5*7}{2*7*5*5}= \frac{6}{10}+ \frac{1}{10}= \frac{7}{10} [/latex] 4) [latex] \frac{15*2}{4*5}- \frac{81*5}{27*25}= \frac{3}{2}- \frac{3}{5}= \frac{9}{10} [/latex]