An investor buys 1 Real Estate for 900 million VND, repair cost 100 VND. Immediately after that, the investor leases the above real estate with the following terms: Lease term 5 years. At the end of each year, tenants must pay 120 million VND. Repair cost per year 5 million VND (investor bears) The deposit is VND 150 million & the investor will refund it when the contract expires. If the expected real estate value is VND 1600 million at the end of the contract, then the investor will sell the above property. Requirements: what is the investor's rate of return