Answer: The required percentage is 25%.
Step-by-step explanation: Given that Mitchell took a math exam today and got 63 out of 84 questions correct.
We are to find the percentage of questions that Michael got wrong.
The number of questions that Michael got correct, n = 63 and
the total number of questions, N = 84.
So, the number of questions that Michael got wrong is
N - n = 84-63 = 21.
Therefore, the percentage of questions that Michael got wrong is

Thus, the required percentage is 25%.