\[\boxed{\mathbf{2.}\mathbf{174}}\]
\[\textbf{а)}\ \frac{7^{\backslash 3}}{40} + \frac{11^{\backslash 2}}{60} = \frac{21}{120} + \frac{22}{120} =\]
\[= \frac{43}{120}\]
\[\textbf{б)}\ \frac{27^{\backslash 3}}{56} - \frac{5^{\backslash 4}}{42} = \frac{81}{168} - \frac{20}{168} =\]
\[= \frac{61}{168}\]
\[\textbf{в)}\ \frac{11^{\backslash 3}}{72} - \frac{7^{\backslash 4}}{54} = \frac{33}{216} - \frac{28}{216} =\]
\[= \frac{5}{216}\]
\[\textbf{г)}\ \frac{16^{\backslash 4}}{45} + \frac{17^{\backslash 3}}{60} = \frac{64}{180} + \frac{51}{180} =\]
\[= \frac{115}{180} = \frac{23}{36}\ \]