zach is planning to invest up to $50 000 in corporate and municipal bonds For one year let extra present the amount he will invest in corporate funds and that why represent the amount you'll invest in municipal bonds. For bonds he also does not want to invest more than 34650 in municipal bonds. The interest is 8.5% in corporate bonds and 6.8% on municipal bonds. This is the simplest interest for one year what is the maximum amount of interest that can earn from his investments?

I already figured out the answer. I need help with question #7. not sure how this method is better than the method of trial and error.

#7) What is the benefit of using this method over the method of trial and error