Let \( x \) be the number of hotdogs sold and \( y \) be the number of corndogs sold. The total amount collected can be represented by the equation:
\[ 3x + 1.5y = 201 \]
This equation states that the total revenue from selling \( x \) hotdogs at $3 each and \( y \) corndogs at $1.50 each equals $201.