Let x be the total amount collected at the door. Then, we can write
[tex]3000+(0.02\times x)=3540[/tex]where the 0.02 denotes the comission of 2%. From this equation, we can find x.
Then, by moving 3000 to the right hand side, we have
[tex]\begin{gathered} 0.02x=3540-3000 \\ \end{gathered}[/tex]which gives
[tex]0.02x=540[/tex]Now, by moving 0.02 to the right hand side, we get
[tex]x=\frac{540}{0.02}[/tex]then, x is given by
[tex]x=27000[/tex]Therefore, the total amount collected at the door is $ 27 000.