\[\boxed{\mathbf{1}\mathbf{.124}}\]
\[\textbf{а)}\ 4340 \cdot 31 + 65 \cdot 17 = 135\ 645\]
\[\textbf{б)}\ 179\ 800\ :29 - 72 \cdot 78 = 584\]
\[\textbf{в)}\ (607 - 427) \cdot 84\ :36 =\]
\[= 180 \cdot 84\ :36 = 5 \cdot 84 = 420\]
\[\textbf{г)}\ 68 \cdot (256 + 144)\ :340 =\]
\[= 68 \cdot 400\ :340 = 2720\ :34 =\]
\[= 80\]