How to calculate Covariance Matrix and Principal Components for PCA? (NO CODE IS REQUIED, JUST SOLUTION)

The dataset with two features (x,y,z) is shown as follows :

X(-1,-1),

Y (0,0),

Z(1,1)

a) Calculate the Covariance Matrix.

b) Calculate eigenvalues and eigenvectors

c) Calculate all the PCs

d) How much percent of the total variance in the dataset is explained by each PC?