student enrollment at a local school is concerning the community because the number of students has dropped to 504 which is a 20% decrease from the previous year. what was the student enrollment the previous year?

For this case, we have 504 students and the student enrollment has decrease 20%, which mean 504 is the 80% of the total student enrollment of the previous year.

[tex]100 - 20 = 80[/tex]%

This is a direct proportion problem. As shown bellow:

504 -> 80%

x -> 100%

For solving this we use the Mathematical Rule of Three, a method of having three numbers to help calculate the unknown.

b -> c

x -> a

The algorithm for rule of three is the following:

[tex]x = \frac{a * b}{c} \\\\x= \frac{504*100}{80} =\frac{50400}{80}=630\\ \\x=630[/tex]