271. Найдите значение выражения, предварительно сократив дроби: 1) \(\frac{25}{80} + \frac{45}{60}\) 2) \(\frac{20}{45} + \frac{26}{54}\) 3) \(\frac{36}{300} + \frac{12}{40} - \frac{350}{1000}\) 4) \(\frac{14}{24} - \frac{39}{90} + \frac{15}{100}\) 5) \(\frac{42}{120} + \frac{20}{32} - \frac{28}{160}\) 6) \(\frac{45}{72} - \frac{33}{144} - \frac{20}{64}\)

Решение: 1) \(\frac{25}{80} + \frac{45}{60} = \frac{5}{16} + \frac{3}{4} = \frac{5}{16} + \frac{3 * 4}{4 * 4} = \frac{5}{16} + \frac{12}{16} = \frac{17}{16}\) 2) \(\frac{20}{45} + \frac{26}{54} = \frac{4}{9} + \frac{13}{27} = \frac{4 * 3}{9 * 3} + \frac{13}{27} = \frac{12}{27} + \frac{13}{27} = \frac{25}{27}\) 3) \(\frac{36}{300} + \frac{12}{40} - \frac{350}{1000} = \frac{3}{25} + \frac{3}{10} - \frac{7}{20} = \frac{3 * 4}{25 * 4} + \frac{3 * 10}{10 * 10} - \frac{7*5}{20*5} = \frac{12}{100} + \frac{30}{100} - \frac{35}{100} = \frac{7}{100}\) 4) \(\frac{14}{24} - \frac{39}{90} + \frac{15}{100} = \frac{7}{12} - \frac{13}{30} + \frac{3}{20} = \frac{7 * 5}{12 * 5} - \frac{13 * 2}{30 * 2} + \frac{3*3}{20*3} = \frac{35}{60} - \frac{26}{60} + \frac{9}{60} = \frac{18}{60} = \frac{3}{10}\) 5) \(\frac{42}{120} + \frac{20}{32} - \frac{28}{160} = \frac{7}{20} + \frac{5}{8} - \frac{7}{40} = \frac{7 * 2}{20 * 2} + \frac{5 * 5}{8 * 5} - \frac{7}{40} = \frac{14}{40} + \frac{25}{40} - \frac{7}{40} = \frac{32}{40} = \frac{4}{5}\) 6) \(\frac{45}{72} - \frac{33}{144} - \frac{20}{64} = \frac{5}{8} - \frac{11}{48} - \frac{5}{16} = \frac{5 * 6}{8 * 6} - \frac{11}{48} - \frac{5*3}{16*3} = \frac{30}{48} - \frac{11}{48} - \frac{15}{48} = \frac{4}{48} = \frac{1}{12}\) Ответы: 1) \(\frac{17}{16}\) 2) \(\frac{25}{27}\) 3) \(\frac{7}{100}\) 4) \(\frac{3}{10}\) 5) \(\frac{4}{5}\) 6) \(\frac{1}{12}\)