Air contains $5$ ppm of ammonia $($TLV$-$TWA of $5$ppm$),22$ ppm of methylcylonite $($TLV$-$TWA of $50$ ppm$),$ and $5$ ppm of difucylacrylimide $($TLV$-$TWA of $2$ ppm$).$ What is the mixture TLV$-$TWA?