A tank with the vertical sides measuring 3m $\times$ 3 m contains water to a depth of 1.2m. An oil of density 900 kg/m3 was poured in the tank up to a depth of 0.8 m. The vertical wall can withstand the thrust of 58 kN. Calculate the actual thrust on the wall and centre of pressure. If the oil level is increased up to 0.9 m, what will be stability of the wall?