15.Вычисли. 5/12 + 1/36 = ... 16.Вычисли. 8/9 - 5/9 = ... 17.Вычисли. 7/8 - 3/4 = ... 18.Вычисли. 11/72 - 1/9 = ...

**Ответ:** **15. Вычисли:** - $\frac{5}{12} + \frac{1}{36} = \frac{15}{36} + \frac{1}{36} = \frac{16}{36} = \frac{4}{9}$ - $\frac{5}{36} + \frac{1}{18} = \frac{5}{36} + \frac{2}{36} = \frac{7}{36}$ - $\frac{1}{72} + \frac{7}{12} + \frac{11}{36} = \frac{1 + 42 + 22}{72} = \frac{65}{72}$ - $10\frac{1}{36} + 2\frac{1}{108} = 10\frac{3}{108} + 2\frac{1}{108} = 12\frac{4}{108} = 12\frac{1}{27}$ - $\frac{5}{18} + \frac{3}{28} + \frac{7}{12} = \frac{70 + 27 + 147}{252} = \frac{244}{252} = \frac{61}{63}$ - $\frac{3}{14} + \frac{8}{21} + \frac{7}{15} = \frac{45 + 80 + 98}{210} = \frac{223}{210} = 1\frac{13}{210}$ - $3\frac{2}{15} + 1\frac{1}{10} + 2\frac{3}{25} = 3\frac{20}{150} + 1\frac{15}{150} + 2\frac{18}{150} = 6\frac{53}{150}$ - $1\frac{7}{24} + 3\frac{7}{120} + \frac{7}{160} = 1\frac{140}{480} + 3\frac{28}{480} + \frac{21}{480} = 4\frac{189}{480} = 4\frac{63}{160}$ **16. Вычисли:** - $\frac{8}{9} - \frac{5}{9} = \frac{3}{9} = \frac{1}{3}$ - $\frac{19}{20} - \frac{7}{26} = \frac{247 - 70}{260} = \frac{177}{260}$ - $5\frac{7}{10} - \frac{3}{10} = 5\frac{4}{10} = 5\frac{2}{5}$ - $4\frac{5}{12} - 3\frac{1}{12} = 1\frac{4}{12} = 1\frac{1}{3}$ - $1 - \frac{1}{3} = \frac{2}{3}$ - $1 - \frac{17}{50} = \frac{33}{50}$ - $2 - \frac{5}{8} = 1\frac{3}{8}$ - $4 - \frac{11}{16} = 3\frac{5}{16}$ **17. Вычисли:** - $\frac{7}{8} - \frac{3}{4} = \frac{7}{8} - \frac{6}{8} = \frac{1}{8}$ - $\frac{1}{2} - \frac{3}{8} = \frac{4}{8} - \frac{3}{8} = \frac{1}{8}$ - $4\frac{7}{8} - 1\frac{3}{4} = 4\frac{7}{8} - 1\frac{6}{8} = 3\frac{1}{8}$ - $5\frac{1}{2} - \frac{3}{8} = 5\frac{4}{8} - \frac{3}{8} = 5\frac{1}{8}$ - $\frac{3}{4} - \frac{5}{12} = \frac{9}{12} - \frac{5}{12} = \frac{4}{12} = \frac{1}{3}$ - $\frac{5}{6} - \frac{17}{24} = \frac{20}{24} - \frac{17}{24} = \frac{3}{24} = \frac{1}{8}$ - $1\frac{1}{3} - 1\frac{1}{12} = 1\frac{4}{12} - 1\frac{1}{12} = \frac{3}{12} = \frac{1}{4}$ - $3\frac{5}{24} - 1\frac{1}{48} = 3\frac{10}{48} - 1\frac{1}{48} = 2\frac{9}{48} = 2\frac{3}{16}$ **18. Вычисли:** - $\frac{11}{72} - \frac{1}{9} = \frac{11 - 8}{72} = \frac{3}{72} = \frac{1}{24}$ - $\frac{11}{24} - \frac{5}{12} = \frac{11 - 10}{24} = \frac{1}{24}$ - $\frac{17}{36} - \frac{7}{18} = \frac{17 - 14}{36} = \frac{3}{36} = \frac{1}{12}$ - $\frac{19}{40} - \frac{9}{20} = \frac{19 - 18}{40} = \frac{1}{40}$ - $15\frac{4}{27} - 8\frac{8}{63} = 15\frac{28}{189} - 8\frac{24}{189} = 7\frac{4}{189}$ - $13\frac{1}{4} - 2\frac{2}{15} = 13\frac{15}{60} - 2\frac{8}{60} = 11\frac{7}{60}$ - $8\frac{5}{42} - 3\frac{3}{56} = 8\frac{20}{168} - 3\frac{9}{168} = 5\frac{11}{168}$ - $10\frac{1}{11} - 9\frac{1}{121} = 10\frac{11}{121} - 9\frac{1}{121} = 1\frac{10}{121}$