Question 936112
Assuming trying to match exactly $6000, let x be advanced tickets, y be same-day tickets,

{{{20x+30y=6000}}}
{{{2x+3y=600}}}



All tickets advanced sales means y=0,
and {{{2x=600}}}
{{{x=300}}}


All tickets same-day means x=0,
and {{{3y=600}}}
{{{y=200}}}


Graphing is simple because you have x and y intercepts.  Look for any combination of tickets but
only accept whole number values for any (x,y) points.