Set up an equation that can be used to solve the problem. Solve the equation and determine the desired value. At a boating and sports store, the cost of renting a personal watercraft is $\$ 36.40$ per half hour, which includes a $4 \%$ sales tax. Determine the cost of a half hour rental before tax. The equation is $\square$ The cost of a half hour rental is $\$ \square$ per half hour. (Type an equation using $x$ as the variable.)

Step 1 ：Set up an equation that can be used to solve the problem. Let the cost of a half hour rental before tax be represented by \(x\). The total cost of the rental, including a 4% sales tax, is given as $36.40. Therefore, the equation is \(1.04x = 36.40\).

Step 2 ：Solve the equation to find the value of \(x\).

Step 3 ：The solution to the equation is \(x = 35.00\). This means that the cost of a half hour rental before tax is $35.00.

Step 4 ：Final Answer: The equation is \(1.04x = 36.40\). The cost of a half hour rental is \(\boxed{35.00}\) per half hour.