Sati was studying neutralisation reaction. She accidentally dropped $$x$$ grams of a sodium carbonate monohydrate into a $$100\,\mathrm{mL}$$ solution of $$\mathrm{HCl}$$ whose concentration was $$0.25\,\mathrm{M}$$. $$10\,\mathrm{mL}$$ from this final solution was taken and titrated against $$0.05\,\mathrm{M}$$ $$\mathrm{NaOH}$$ solution to yield a titre value of $$20\,\mathrm{mL}$$. What is the value of $$x$$.