\[\boxed{\text{5.\ 114}}\]
\[\textbf{а)}\ 7,3x + 4x = 11,3x\]
\[\textbf{б)}\ 3a - 5a = - 2a\]
\[\textbf{в)}\ n - \frac{4}{5}n = \frac{1}{5}n\]
\[\textbf{г)} - \frac{5}{7}m + m = \frac{2}{7}m\]
\[\textbf{д)}\ 2,1x + 4,5x - 1,9x =\]
\[= 6,6x - 1,9x = 4,7x\]
\[\textbf{е)}\ \frac{7}{11}a + \frac{8}{11}a - \frac{4}{11}a = \frac{11}{11}a =\]
\[= a\ \]
\[\textbf{ж)} - 6a - a + 7 = - 7a + 7\]
\[\textbf{з)}\ 9n - 5y - 4n + 7y =\]
\[= 5n + 2y\]
\[\textbf{и)}\ 3,6x + 5,1y - 2,9x - 4,2y =\]
\[= 0,7x + 0,9y\]