\[\boxed{\mathbf{6.98}}\]
\[\textbf{а)}\frac{7}{8} + \frac{3}{4} = \frac{7}{8} + \frac{6}{8} = \frac{13}{8} = 1\frac{5}{8}\]
\[\textbf{б)}\frac{7}{8} - \frac{3}{4} = \frac{7}{8} - \frac{6}{8} = \frac{1}{8}\]
\[\textbf{в)}\ \frac{8}{9} \cdot \frac{7}{16} = \frac{7}{18}\]
\[\textbf{г)}\ \frac{7}{8}\ :\frac{3}{4} = \frac{7}{8} \cdot \frac{4}{3} = \frac{7}{6} = 1\frac{1}{6}\]
\[\textbf{д)}\ 0,7 + 0,43 = 1,13\]
\[\textbf{е)}\ 0,7 - 0,43 = 0,27\]
\[\textbf{ж)}\ 0,7 \cdot 0,43 = 0,301\]
\[\textbf{з)}\ 0,7\ :0,43 = 70\ :43 = \frac{70}{43} =\]
\[= 1\frac{27}{43}\]