3\4 - 1\6 = \frac{18}{24} - \frac{4}{24} = \frac{14}{24} = \frac{7}{12}

5\6 + 1\9 = \frac{45}{54} + \frac{6}{54} = \frac{51}{54} = \frac{17}{18}

8\25 + 17\20 = \frac{160}{400} + \frac{425}{400} = \frac{585}{400}

4\45 - 1\30 = \frac{120}{135} - \frac{9}{270} = \frac{240}{270} - \frac{9}{270} = \frac{231}{270}

17\18 - 11\12 = \frac{306}{324} - \frac{264}{324} = \frac{42}{324} = \frac{7}{54}

11\15 + 5\12 = \frac{165}{180} + \frac{75}{180} = \frac{240}{180} = \frac{4}{3}