The effective combined tax rate in an owner-managed corporation is 40%. An outlay of $20,000 for certain new assets is under consideration. It is estimated that for the next 8 years. These assets will be responsible for annual receipts of $9,000 and annual disbursements (other than for income taxes) of $4,000. After this time, they will be used only for standby purposes, and no future excess of receipts over disbursements is expected. What is the prospective ROR before income taxes? What is the prospective ROR after taxes if these assets can be written off for tax purposes in 8 years using straight-line depreciation? What is the prospective ROR after taxes if it is assumed that these assets must be written off over the next 20 years using straight-line depreciation?