The average steady$-$state plasma concentration after administering $800$ mg sustained release drug product every $24$ hours to a $78kg$ male subject $(5$ feet $2$ inches$)$ is $15u\frac{g}{m}L.$ The volume of distribution is $40L.?($assuming $100\%$ bioavailability; F$=1)($Q$2,$ Q$3,$ Q$4)$

What is the drug's clearance?