$10\mathrm{.}1$ Users A and B use the Diffie$-$Hellman key exchange technique with a common prime q $=71$ and a primitive root o $=7.$

If user A had a private key Xa $=5,$ what is A$$s public key Ya$?$

If user B had a private key Xb $=12,$ what is B$$s public key Yb$?$

What is the charred secret key?