To find the percent of error divide how off the wrong answer was by the right number, then multiply by 100.
Bryan's guess of 730 was 120 less than the actual number so you would divide 120 by 850. 120/850 = 0.141
Then we would multiply that by 100. 0.141 * 100 = 14.1
His percent of error was 14.1%. The percent of error is negative since his guess was less than the right answer.
