From one year to the next, the population of a middle school dropped from 680 to 520. Which of the following is closest to the percent that the population decreased?
(1) 12%
(3) 24%
(2) 17%
(4) 31%

A) {2,4,5,11}

{(2,3),(4,7),(5,9),(11,6)}

The numbers are given in ordered pairs (x,y)

First number is x  and the second number is y

x values are : 2, 4, 5, 11

y values are : 3, 7 , 9 , 6

Domains of a function are the set of x values

so for domain  we take all the x values and we write inside the brackets { }

Domain  is {2, 4, 5, 11}