<p>A slope of -4/5 means “go down 4, right 5” to get from one point to the next. For example, if you start at (0,0) then the next point would be (5,-4). The reflection of this point in the x-axis is (5,4). So from (0,0) you go up 4, right 5. Thus, the slope is 4/5.</p>