The $\mathrm{pH}$ of an aqueous solution containing $1 \mathrm{M}$ benzoic acid $\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$ and $1 \mathrm{M}$ sodium benzoate is 4.5. The volume of benzoic acid solution in $300 \mathrm{~mL}$ of this buffer solution is _________ $\mathrm{mL}$. (given : $\log 2=0.3$)