\[\boxed{\mathbf{3.}\mathbf{329}}\]
\[\textbf{а)}\ 5 \cdot 2^{4} + 7^{2} = 5 \cdot 16 + 49 =\]
\[= 80 + 49 = 129\ \]
\[\textbf{б)}\ \left( 9^{3} - 3^{3} \right)\ :3^{2} =\]
\[= (729 - 27)\ :9 = 702\ :9 = 78\]
\[\textbf{в)}\ 8^{3} - 4 \cdot 5^{2} = 512 - 4 \cdot 25 =\]
\[= 512 - 100 = 412\]
\[\textbf{г)}\ 10^{4} \cdot \left( 5^{3} + 5^{2} \right) =\]
\[= 10\ 000 \cdot (125 + 25) =\]
\[= 10\ 000 \cdot 150 = 1\ 500\ 000\]