Investco wants to invest money that would generate an annual yield of at least $20,000. Two stock groups are available: bank stocks and tech stocks, with average annual yields of 15% and 25%, respectively. Though tech-stock provide a higher yield, they are more risky, and Investco wants to limit the amount invested in these stocks to no more than 75% of the total investment. What is the minimum amount of Investco should invest in each stock group to accomplish this investment goal?