6. [20] Your uncle is considering growing grapes in North Hidalgo County. He hopes to make 12% on his investment. The planting of the grape vines will cost him $20,000, and the grape vines take 4 years to mature (no grapes for the first four years). Then, the grape vines yield good grapes for 8 years. How much should the grape crops sell for each year for those eight years to make this investment viable