To calculate the total cost for Tyra to go to the fair, we need to consider both the entrance fee and the cost of the ride tickets.
The entrance fee is $12. Each ride ticket costs \( d \) dollars, and if Tyra buys 20 tickets, the cost for the tickets would be \( 20d \).
Therefore, the total cost for Tyra would be the entrance fee plus the cost of the tickets:
\[ \text{Total cost} = 12 + 20d \]
So the correct answer is:
$12 + 20d