Question 993289
No need to solve for number of tickets sold.  The description gives x=200.


You can solve for s, how many student tickets and y, how many adult tickets.
{{{system(3s+6y=840,s+y=200)}}}


{{{system(s+2y=280,s+y=200)}}}


Subtract the two equations
{{{highlight(y=80)}}}
and {{{highlight(s=120)}}}.