$50.0\mathrm{mL}$ of water containing only $\mathrm{Na}{}_2\mathrm{CO}{}_3$ and $\mathrm{NaHCO}{}_3$ as alkalinity is titrated with $0.0200\mathrm{M}$ $\mathrm{HCl}$. The phenolphthalein end point ($\mathrm{CO}{}_3{}^{2-}\to \mathrm{HCO}{}_3{}^{-}$) is reached at $3.0\mathrm{mL}$ and the methyl orange end point (total, all carbonate species to $\mathrm{H}{}_2\mathrm{CO}{}_3$) at $11.0\mathrm{mL}$ from the start. Taking the molar mass of $\mathrm{NaHCO}{}_3$ as $84$, find the $\mathrm{NaHCO}{}_3$ originally present in mg/L (nearest integer).

Numerical answer type, answer in mg/L, tolerance 1.