Feasibility to configure Hours Purchase Benefit Rate Calculation

Summary: Suggestions are welcome on Benefit Rate Calculations that are derived from Number of Hours as inputted by worker while making elections:

User to input number of hours while making elections and rate to be calculated as Annual salary / Weeks in year / Contractual weekly hours * Hours purchased (user inputted number) / 12 Months = Gross monthly reduction in salary.

Content (please ensure you mask any confidential information): Existing Methods give either User Inputted, Or calculation, not both simultaneously

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Code Snippet (add any code snippets that support your topic, if applicable):