Сложить и вычесть обыкновенные дроби. 5/18+1/9; 66/84+39/42; (3/8-1/9)+25/36; 2/3-7/16;...

Решите задачу:

$1. \frac{5}{18} + \frac{1}{9} = \frac{5}{18} + \frac{2}{18} = \frac{7}{18}$
$2. \frac{66}{84} + \frac{39}{42} = \frac{33}{42} + \frac{39}{42} = \frac{72}{42} = \frac{12}{7}=1 \frac{5}{7}$
$3. ( \frac{3}{8}- \frac{1}{9})+ \frac{25}{36}=\frac{3}{8}-\frac{1}{9}+ \frac{25}{36}= \frac{3}{8}- \frac{4}{36}+ \frac{25}{36}= \frac{3}{8}+ \frac{21}{36}= \frac{27}{72}+ \frac{42}{72}= \frac{69}{72}$
$4. \frac{2}{3} -\frac{7}{16} =\frac{32}{48} - \frac{21}{48} = \frac{11}{48}$
$5. \frac{59}{64} - \frac{21}{32} = \frac{59}{64} -\frac{42}{64}= \frac{17}{64}$
$6. ( \frac{8}{9}- \frac{5}{6})+ \frac{2}{3}= \frac{8}{9}- \frac{5}{6}+ \frac{6}{9}= \frac{14}{9}- \frac{5}{6}= \frac{28}{18}- \frac{15}{18}= \frac{13}{18}$