The answer would be ay-xb
There are 13 hearts in a 52 deck.
You can think about it like this:
P = (13/52)*(12/51)*(11/50)*(10/49)*(9/48)*(8/47) = 0.00008428903476
(1,3) and (7,3) falls on the same horizontal line. hence, the distance is just equal to 6 units. (7,3) and (7,7) meanwhile lie on the same vertical line. hence the distance is 4. (7,7) and (4,7) lie on the same horizontal line with a distance of 3.
Finally, to get back to point (1,3) - (4,7) ----> (1,3), 3 to the left and 4 down, the diagonal being 5.
6+4+3+5= 10 + 8 = 18.