Number of collisions of molecules of a gas on the wall of a container per  $m^2$  will :

No. of collisions per unit area
               $\infty \frac{1}{timebetweentwocollision\times area}$
n/A ∞ $\frac{{\text{ V}}_{rms}}{\text{ distance b/w walls }\times A}$  
                 $V₁$ rms ∞  $\sqrt{T}$

  distance b/w walls x A volume

            So $\frac{n}{A}$ ∞  $\frac{T^{1/2}}{v}$

   if both T and V are halved,  $\frac{n}{A}$  increases.