Answer
Set: {10♦,10♣,10♠,10♥,J♦,J♣,J♠,J♥,Q♦,Q♣,Q♠,Q♥,K♦,K♣,K♠,K♥,A♦,A♣,A♠,A♥}
Probability: 20/52, or 38.5%
Work Step by Step
The event that the card denomination is 10 or higher includes all 4 suits of 10, J, Q, K, and A, giving you 20 total cards. The probability then is 20/52, or 38.5%