Basically, it is not a function because 1 domain (in this case, 5) can not be connected to two different ranges(1 and -2). Each domain must only connect to one range.
        
             
        
        
        
Since you didn't list choices, I can only give you some guidance on the problem.
A kilometer is the length of 1000 meters. And a meter is about as tall as a normal desk height. So a kilometer is a relatively long distance compared to a desk.
It is also about half the length of a mile, or about 2 times around a normal athletic track.
Look for items that are long distance like that.
        
             
        
        
        
Step-by-step explanation:
If it's a straight line the use formula

m= gradient of line
c = y-intercept
we know that y-intercept is 4 so coordinate is
(0,4)
Equation also passes (2,10)
Use both coordinate to find gradient
m= vertical distance / horizontal distance
 = (10-4) / (2-0)
 = 3
y = 3x + 4