take the final amount of students (1128) and divide it by the beginning amount (1200) this will give you the percent of kids that stayed in the school, in decimal form .94, you can now multiply by 100 to get the percentage form of students that stayed, then subtract 94% from 100% to see that there was a 6% decrease in the number of students
if you have any questions, leave them in the comments and i will try to answer them.
