Michael, an Internet service provider, bought an existing business worth $200,000 on December 31, 2017. During 2018, his business grew and he bought $300,000 of new servers. The market value of his older servers fell by $50,000. What was Michael's gross investment, depreciation and net investment during 2018? Michael's gross investment during 2018 was $ Michael's depreciation during 2018 was $ Michael's net investment during 2018 was $