y = mx + b 
Where m = slope and b is the y intercept 
Let's find the slope = change in y/change in x 
m = (4-2)/(-6+2) = 2/-4 = -1/2 
Now we have: 
y = (-1/2)x + b 
Now substitute point (-6,4) 
4 = (-1/2)(-6) + b 
4 = 3 + b 
b = 1 
 
So y = (-1/2)x + 1 is the equation.