The cost of the entrance ticket is $6.
The equation that can be used to represent the information in the question is:
Total cost = (number of students x entrance fee) + (cost to rent a skate x number of students)
$81 = 9t + ($3 x 9)
$81 =9t + $27
In order to determine the value of t, the following steps would be taken:
Combine similar terms
$81 - $27 = 9t
Subtract similar terms
54 = 9t
Divide both sides of the equation by 9
t = $6
To learn more, please check: https://brainly.com/question/13813779