$9-20$ A short distance downstream from the Waramurungundi tannery in $$ Problem $9-19,$ a glue factory and a municipal wastewater treatment plant also discharge into Djanggawul Creek. The wastewater flows and ultimate $BO{D}_5$ for these discharges are listed in the following table. Betermine the initial ultimate BOD after mixing of the creek and the three wastewater discharges.

$\backslash$table$[[$Source$,$Flow $(m^3*s^{-1}),$Ultimate BOD $(mg*L^{-1})$