For the decomposition reaction ${\mathrm{NH}}_2{\mathrm{COONH}}_4\left(\mathrm{s}\right)\rightleftharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$,  the $K_p=2.9\times {10}^{-5}{\mathrm{atm}}^3$. The total pressure of gases at equilibrium when $1.0\mathrm{mol}$ of ${\mathrm{NH}}_2{\mathrm{COONH}}_4\left(\mathrm{s}\right)$ was taken to start with would be