Can u help me on the mystery sequence hidden in the dominoes

Answer: 80
Step-by-step explanation:
A) The first domino is 3, the second is 4. Hence 34.
B) The first domino is 5, the second is 1. Hence 51.
C) The first domino is 6, the second is 11. Hence 71.
D) The first domino is 7, the second is 10. Hence 80.