9 out of Reagan's 15 classmates go to bed at 10 p.m.
As a fraction, this would be 9/15.
To convert a fraction to a decimal, you just divide the numerator by the denominator.
Thus, 9 ÷ 15 = 0.6
To turn a decimal into a percentage, you multiply the decimal by 100, and then add a percentage sign.
0.6 * 100 = 60%
Therefore, 60% of Reagan's classmates go to bed at 10 p.m.
Hope this helps!