Hello, thank you for taking the time to post your question!
Because the function here is perpendicular that means that the slop will be the opposite reciprocal, so m = -7/8
From there then we can plug in the slope and the point (2, 8) to figure out what the corresponding y-intercept is for this scenario
8 = -7/8(2) + b
8 = -14/8 + b
8 + 14/8 = b
b = 39/4
putting it all together then the equation of the line here is
y = -7/8x + 39/4
I hope that helps you get moving in a better direction on this type of question! Feel free to reach out if you have any additional questions beyond that :)