Hello!
To find a percentage, we will need to divide the number of things specified, by the total number given.
Once you complete that step, you should get a decimal.
Then, you should multiply that decimal by 100 to get it to a decimal.
We are given that 31 students out of 82 students play a brass instrument in a high school band. So, we would divide 31 by 82, and then multiply.
31/82 = 0.3780
0.3780 x 100 = 37.8%
Therefore, 37.8% of students play a brass instrument.