\[\boxed{\mathbf{2}\mathbf{.}\mathbf{45}}\]
\[1)\ 44 - 14 \cdot 6\ :28 =\]
\[= 44 - 84\ :28 = 44 - 3 = 41\]
\[2)\ 2511\ :31 \cdot 13 - 164 = 889\]
\[3)\ (73 \cdot 310 - 17\ 554)\ :47 =\]
\[= 108\]
\[4)\ (4515\ :43 + 145) \cdot 84 =\]
\[= (105 + 145) \cdot 84 = 250 \cdot 84 =\]
\[= 21\ 000\]