You can
put this solution on YOUR website!Let's assign variables to the different groups so we can later solve this system with either substitution or elimination.
Student tickets = s
adult tickets = a
So, translate the english into math.
Since a total of 691 tickets were sold, we can derive the equation:
Then, there were 59 fewer students sold, that means more adult tickets were sold.
Now put these in a system of equations and solve.
For this system, I would suggest substitution because there is already an isolated variable.
We now know that

adult tickets were sold.

student tickets were sold.
Hope this helps!