Let the number of floor tickets sold be x.
Let the number of balcony tickets sold be y.
According to the first condition,
[tex]x\text{ + y = 500\_\_\_\_\_\_\lparen1\rparen }[/tex]The total amount collected is $ 14000.
According to the second condition,
[tex]20x\text{ + 30y = 14000\_\_\_\_\_\_\_\lparen2\rparen}[/tex]Multiplying equation (1) by 20,
[tex]20x\text{ + 20y = 10000\_\_\_\_\_\lparen3\rparen}[/tex]Subtracting equation (3) from (2),
[tex]\begin{gathered} 10y\text{ = 4000} \\ y\text{ = 400} \end{gathered}[/tex]Substituting x = 400 in equation (1),
[tex]\begin{gathered} x\text{ + y = 500} \\ 400\text{ + y = 500} \\ x\text{ = 100} \end{gathered}[/tex]Thus a number of floor tickets sold is 100 and the number of balcony tickets sold is 400.