In $2005,$ U$.$S$.$ landfills emitted approximately $7000Gg$ of methane emissions, and wastewater treatment plant emitted $1800Gg$ of methane. How many $Tg$ of $C{O}_2$ equivalents did landfills and wastewater treatment plant emit in $2005?$ What percent of the total $2005$ methane emissions $($and GHG emissions$)$ do these two sources contribute? $($Total methane emissions in $2005$ were $600TgC{O}_{2}e,$ and total $GHG$ emission were $7500C{O}_2$ e$)$