1. The problem states that to join a dancing club, there is a $30 startup fee and a $4 monthly fee. 2. In word problems involving fees, the constant usually refers to the fixed amount that does not change with time or usage. 3. Here, the $30 startup fee is a one-time fixed cost, while the $4 monthly fee varies depending on the number of months. 4. Therefore, the constant in this problem is the startup fee, which is $30. Final answer: The constant is $30.