$$910.$ Oscar will owe a combined penalty of $26$ percent, which consists of a late payment penalty of $3\mathrm{.}5$ percent $(7$ months $\backslash$times $0\mathrm{.}5$ percent late payment penalty$)$ and a late filing penalty of $22\mathrm{.}5$ percent $(5$ months $\backslash$times $5$ percent per month $=25$ percent, less the $0\mathrm{.}5$ percent late payment penalty that applies during the same $5$ months, $5$ months $\backslash$times $0\mathrm{.}5$ percent $=2\mathrm{.}5$ percent$).$