Suppose a company uses straight-line depreciation. Its equipment costs $23 million, has accumulated depreciation of $8 million and annual depreciation expense of $2 million. Its building costs $1,523 million, has accumulated depreciation of $380 million, and annual depreciation expense of $42 million. (a) What are the average ages of the equipment and building respectively? (b) What are the average useful lives of the equipment and building respectively