4. [5] A company expects the following revenues and expenses during the next year. The state income tax rate is a flat 6% rate, and state taxes are a deductible item for federal tax calculations Revenues Expenses 480,000 Labor Equipment Depreciation Materials Supplies Rent Insurance 75,000 40,000 15,000 30,000 75,000 20,000 a. If state income taxes were zero, what would be the amount of federal income tax? b. If state income taxes were zero, what would be the effective (average) federal income tax rate for this company? c. If state income taxes were zero, what would be the marginal federal income tax rate? d. With state income taxes at the flat rate given above, what is the amount of state income tax