Knowing that the club members have to pay $3,
The equation would be: y=$3x+$30
Where y is the total cost and x is the number of tickets/entry.
Non-club members:
y=$6x+30
Find their intersection to find at what point both members would be pay equally.
$6x+$30=$3x+30 (knowing that their y values should be the same, we can equal them)
6x=3x +30-30
6x-3x=0
3x=0
x=0
Therefore, at 0, both members would be paying the same amount, $30.
Hope I helped :)