Let's assume that the regular price of each ticket is p dollars.
Since Dea buys 6 tickets at $1.50 off the regular price, the cost of each ticket is p - $1.50.
Dea buys 6 tickets at this cost, so her total cost is 6(p - $1.50).
According to the problem, her total cost is $51.
Therefore, we can write the equation: 6(p - $1.50) = $51.
Now, let's solve for p:
6p - (6 * $1.50) = $51
6p - $9 = $51
6p = $51 + $9
6p = $60
p = $60 / 6
p = $10
Therefore, the regular price of each ticket is $10.
Explanation: We set up the equation 6(p - $1.50) = $51 to represent the cost of 6 tickets with a discount as Dea's total cost. Then we solved the equation to find that the regular price of each ticket is $10.