Harriet and Harry Combs $($both $37$ years old$)$ are married, and both want to contribute to a Roth IRA. In $2023,$ their AGI before any IRA contribution deductions is $$50,000.$ Harriet earned $$46,000$ and Harry earned $$4,000.$

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a$.$ How much can Harriet contribute to her Roth IRA if they file a joint return? b$.$ How much can Harriet contribute if she files a separate return?