[tex]\frac{7}{8}+\frac{3}{4}=\frac{7}{8}+\frac{6}{8}=\frac{13}{8}; \\ \frac{11}{12}-\frac{7}{18}=\frac{33}{36}-\frac{14}{36}=\frac{19}{36}; \\ \frac{5}{12}+\frac{3}{16}=\frac{20}{48}+\frac{9}{48}=\frac{29}{48}; \\ \frac{5}{7}-\frac{3}{5}=\frac{25}{35}-\frac{21}{35}=\frac{4}{35}.[/tex]