Which set of output values correctly complete the function table?
y= -4x
input (x) output (y)
-6 ?
-2 ?
3 ?

You want to find your output (which is y) 
and to find y, you must multiply by the values of x by -4 

so all you do here is put the input numbers (which represent x) and substitute that into the x spot to give you y!! 

so for -6 this is what you'd do 
y=-4x 
x=-6
y= -4(-6) 
=24 (because remember, when multiplying, 2 -'s make a +) 

for -2 it's the same thing 
y=-4x 
x=-2 
so y= -4(-2) 
=8 

for 3 also, 

y=-4x 
x= 3
y=-4(3) 
= -12

Hope that makes sense :) !