Final answer:
The deductible amount for the cost of the dinner and theatre remains at $235, which represents 50% of the total expense ($470) according to typical IRS rules for business entertainment expenses.
Step-by-step explanation:
The deductible amount for the cost of the dinner and theatre, if the cost represents a business entertainment expense typically adhering to IRS rules, would be the stated 50% of the total cost. Therefore, if $235 represents 50% of the total cost, this means the taxpayer incurred a total cost of $470. The deductible amount thus remains at $235, as initially mentioned in the question.