a. Show that E(Xi.. - X...) = i, so that Xi.. - X.. is an unbiased estimator

a. Show that E(X̅i.. - X̅...) = αi, so that X̅i.. - X̅.. is an unbiased estimator for αi (in the fixed effects model).
b. With ij = X̅ij.. - X̅i.. - X̅.j. + X̅..., show that ij is an unbiased estimator for γij (in the fixed effects model)?