Normal distribution

A 2-class problem with two-dimensional features x=(x1,x2)T. The class conditional distributions p(x/Ci) are modeled by Gaussian densities with mean b1 =(1,0)T for class 1 and b2 =(-1,0) for class 2.Assume P(C1)=2/3 & P(C2)=1/3 .Write down expressions for the posterior probabilities P(C1/x) &P( C2/x)