\[\boxed{\mathbf{777}\mathbf{.}}\]
\[1)\log_{10}5 + \log_{10}2 =\]
\[= \log_{10}(5 \bullet 2) = \log_{10}10 = 1\]
\[2)\log_{10}8 + \log_{10}125 =\]
\[= \log_{10}(8 \bullet 125) = \log_{10}1000 =\]
\[= \log_{10}10^{3} = 3\]
\[3)\log_{12}2 + \log_{12}72 =\]
\[= \log_{12}(2 \bullet 72) = \log_{12}144 =\]
\[= \log_{12}12^{2} = 2\]
\[4)\log_{3}6 + \log_{3}\frac{3}{2} =\]
\[= \log_{3}\left( 6 \bullet \frac{3}{2} \right) = \log_{3}9 =\]
\[= \log_{3}3^{2} = 2\]