Zach is planning to invest up to $50,000 in corporate and municipal bonds. The least he will invest in corporate bonds is $6000 and he does not want to invest more than $27,000 in corporate bonds. He also does not want to invest more than $34,650 in municipal bonds. The interest is 8.5% on corporate bonds and 6.8% on municipal bonds. This is simple interest for one year. What is the maximum income?

How would I graph that? How would i find the vertices?