Answer: The number of adult tickets sold is 168.
Step-by-step explanation: Given that the Jillian's school is selling tickets for a play. The tickets cost $10.50 for adults and $3.75 for students.
The ticket sales for opening night totaled $2071.50. The equation representing the situation is

where a is the number of adult tickets sold and b is the number of student tickets sold.
We are to calculate the number of adult tickets that were sold.
If 82 students attended, then b = 82.
Substituting the value of b in equation (i), we get

Thus, the number of adult tickets sold is 168.