11.10 out of 15 = 11.1/15 = 111/150
To convert this fraction to a percent, we first need to make the denominator equal to 100. To do that, we need to multiply the 150 by 2/3. And as a rule of fractions, you must multiply the numerator and the denominator by the same number to maintain its value.
(111 * 2/3)/(150 * 2/3) = 74/100
The numerator is your percentage.
11.10 out of 15 = 74%