Jeff assumes that the opposite of what he is trying to prove is true. Jeff has just completed the first step in which geometric process?

Daniel buys one bond each with a par value of $1,000 from grath oil, ombor medical supplies, and dwyn horticulture. grath oil bonds are selling at 120.514, ombor medical supplies bonds are selling at 90.773, and dwyn horticulture bonds are selling at 101.180. what is the total face value of daniel's bonds?