$*$Please show work and explain how you got your answer!

Calculate annual emissions from a $20$ MMBtu$/$hr $($MMBtu denotes a million British thermal units$)$ Natural $-$ Gas $-$ fired boiler while Natural gas higher heating value $($HHV$)=1,020$ Btu$/$scf$.$

$*$MMBtu$/$hr is a unit of measurement for pollutants. MMBtu$/$hr stands for pounds of pollutant per million standard cubic feet of natural gas fired.

$*$HHV or gross heating value, is total heat released during the complete combustion of a unit of fuel.