Please show all steps and explain each step

Problem 7. Let 0 = {w1, W2, w3, w4} and consider the following information structure on Po = {{}, P1 = { {w1, w2}, {w3, WA} }, P2 = {{wi}, {w2}, {wa}, {wa} } If Q(wi) = = for each i = 1, ..., 4, the process X = (Xo = 5, X1, X2) is a martingale with respect (Pi)izo and , if w =w1 6 , if w =W2 X2 (W) = 5 , if w = w3 1 , ifw = WA Calculate x