Sodium bicarbonate decomposes at high temperatures according to the following equation: $2NaHC{O}_3\left(s\right)\rightleftharpoons N{a}_{2}C{O}_3\left(s\right)+H_{2}O\left(g\right)+C{O}_2\left(g\right)$ . At a certain temperature, 50.0 g of $NaHC{O}_3$  is allowed to react in a 6.0 L evacuated vessel. At equilibrium, the total pressure is 4 atm, with some of both solids still present. If 50.0 g of  $NaHC{O}_3$ is allowed to react in a 3.0 L evacuated vessel at the same temperature, what will the pressure (in mmHg) of $C{O}_2\left(g\right)$  be at equilibrium?