1. Let's put this equation in to y = mx + b form (easier for me to visualize)
5x + 8y = -9
8y = -5x - 9
y = -5/8 x - 9/8 slope = -5/8
perpindicular slope = 8/5
We know 10, 10 is on the new line....
y = 8/5 (x) + b
10 = (8/5) 10 + b b = -6
so y = 8/5 x - 6 m + b = -22/5