Explanation:
normal line equation
y = ax + b
the 2 points give us our of that 2 equations with the 2 variables a, b. and we are going to solve that for the general line equation :
3 = a×-2 + b
3 = a×8 + b
let's subtract equation 2 from equation 1
0 = a×-10 + 0
=> a = 0
=> 3 = 0×8 + b
b = 3
the line equation is therefore
y = 3
which is logical, because both given points have the same y value. so, it must be a horizontal line (parallel to the x axis).