Aline passes through the points (0, 2) and (2, –2) .

enter the slope of the line in the box.

(0,2) and (2,-2)
The first number is the x axis, so it goes 2 units from 0 to 2. 
The second number is the y axis, so to goes -4 units from 2 to -4 

Slope is the rate of change per one unit. (on the x axis)
2has to be divided by 2 to get one unit so -4 has to be divided by 2 as well. 
-4/2=-2 
That is your solution