\[\boxed{\mathbf{2.2}\mathbf{58}}\]
\[\textbf{а)}\ 4\frac{3}{5} + 2,6 - 5\frac{1}{2} =\]
\[= 4,6 + 2,6 - 5,5 = 7,2 - 5,5 =\]
\[= 1,7\]
\[\textbf{б)}\ 4\frac{1}{3} + 5,3 - 2\frac{7}{30} =\]
\[= 4\frac{1^{\backslash 10}}{3} + 5\frac{3^{\backslash 3}}{10} - 2\frac{7}{30} =\]
\[= 4\frac{10}{30} + 5\frac{9}{30} - 2\frac{7}{30} =\]
\[= 9\frac{19}{30} - 2\frac{7}{30} = 7\frac{12}{30} = 7\frac{4}{10} =\]
\[= 7,4\]