Hello tutors, can I please get you assistance with the following ? Thank You so much

A restaurant offers a limited menu of three entrees with prices 20, 25, 1nd 30 dollars respectively. We are interested in orders that couples in which only one person in the couple pays order (we are not interested in couples in which the tab is shared).Let X denote what the paying member of the couple orders and Y denotes what the non-paying member of the couple orders. The joint pmf of the behavior of such couples is given by the following pmf.