The amount of students dropped from 1200 to 100 in a 3 year period. What the percent of decrease?

Question

+ explain how you do this.
I know its a percent of decrease equation butttt I don't remember how to do it

Answer 1

Assuming that u wish tto calculate the overall percent decrease over the 3 yr period:
Number of students that decreased = 1200-100=1100
So 1100 students decreased over the initial 1200 students.
percentage decrease = 1100/1200 x 100 = 11/12 x 100
calculate this to get the answer.

there can also be a calculation of percentage of average annual decrease

Answer 2

You subtract 100 from 1200 to get an actual decrease of 1100. Divide 1100 by 1200 and you get .91666. Move the decimal over two places to 91.666. Round it off to get 92%.