[Refactor] Use standard class method rather than an arrow function in RentedLocation class

[Gamez0]

Is your feature request related to a problem? Please describe.
RendtedLocation class is using arrow function when other use standard class method.

Describe the solution you'd like
Change them all to standard class method.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
#56 (review)
copilot review: Consider defining getFee as a standard class method rather than an arrow function for consistency with typical class method declarations.