The number of masks that Mayerlin kept on her wall given the information in the question is 304.
<h3>What are percentages?</h3>
Percentage is the fraction of an amount that is usually expressed as a number out of hundred. Percentages are a measure of frequency.
<h3>How many masks are on the wall?</h3>
Percentage of the masks on the wall = 100 - 24 = 76%
Number of the masks on the wall = 76% x 400 = 304
To learn more about percentages, please check: brainly.com/question/25764815
