At present, there are nine kinds of playing cards with the same backs, the faces are: hearts A, hearts 2, hearts 3, hearts 4, spades A, spades 2, spades 3 and spades 4.

(1) Judging from the meaning of the question, two of the nine cards have the number 3, that is, P = 29.

(2) List:? Red 1 Red 2 Red 3 Red 4 Black 1 (1, 1) (2, 1) (3, 1) (4, 1) Black 2 (/kloc). 4) (4,4) Black 5 (1, 5) (2,5) (3,5) (4,5) has 20 equal possibilities, in which the equation mx2+3x+n4=0 has a real root, that is, △=9-mn≥0, that is, mn≤9.

Then p = 1420 = 7 10.