Slope formula = (y₂- y₁)/(x₂ - x₁) = m
The line passes through 2 points A( x₁, y₁) & B(x₂ y₂)
but we are given A( - 41, 15) & B(- 73, 15). NOW PLUG:
m = (15 - 15) / [( - 73 - ( -41)]
m= 0/(-32) & m =0
(when the slope = 0, this means the line is parallel to x=axis)