15% of 80 is 4 and add that to 80 to get 84. 10 percent of that is 8.4 and add that to the 84 and you get 92.4. So what percent is 80 is 92.4 is the new question? You should know that 8/9 is 87.5%. However, the ratio is greater than 8/9 so therefore the answer has to be less than 87.5%. Without using a calculator, you could eliminate all the wrong answers and find the right one.