(summation over X)(summation over Y) (constant c)(x^2 + y^2)

this is a prabability problem, so the summation should add up to 1 and the goal is to find the value of the constant c.

Am I right to just seperate the summations and do the X's and Y's seperatly?

The reason I am confused is because the following question asks for the probability of Y < X, given that X can only be {1,2,4} and Y can only be {1, 3}.

my probability comes out to be greater then 1.

Please help