$$lg 10000^2 - lg \frac{1}{100^2}$$
$$\\log_{10} 10000^2 - log_{10} \frac{1}{100^2} \\\\ =2*log_{10} 10000 - log_{10} 100^{-2} \\\\ =2*log_{10} 10^4 -\; -2*log_{10} 100 \\\\ =2*4*log_{10} 10 +2*log_{10} 10^2 \\\\ =8*1 +2*2*log_{10} 10 \\\\ =8 +4 \\\\ =12$$