Referring to the random variables whose joint probability distribution is given in Exercise 3.53 find the mean

Question:

Referring to the random variables whose joint probability is given in Exercise 3.53 find the mean for the total number of jacks and kings when 3 cards are drawn without replacement from the 12 face cards of an ordinary deck of 52 playing cards.
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...