The slope of a line that is perpendicular to a line will be a negative reciprocal. When you rewrite 2x-7=8 into slope-intercept form, you get y=2x-8. The negative reciprocal of the slope 2x is -1/2x. There is only one option with this slope. If you're still not sure then you can use a graphing calculator to check this. An online one would be desmos
