A and B are two volatile liquids with their vapour pressure:  $P_A^0=340mmand{P}_B^0=420mmofHgat{25}^{o}C$.To flask containing 8.0 mole of A, 5.0 moles of B was added. As soon as B was added, A starts associating to form a non-volatile substance $A_x\left(solid\right)$  which is soluble in both liquids A and B. The vapour pressures of solutions measured at the end of one hour and after a very long time were found to be 360mm and 300mm of Hg respectively. The total number of moles of A, B and  $A_x\left(solid\right)$ at the end one hour is  $N$ then $(N-5.5)$ is________