Which of the following is true about the relationship between the slopes of the lines whose equations are 8x - 9y = 5 and 9x - 8y = 1?

The answer is they are reciprocal.

(1) Express both equations in the slope-intercept form: y = mx + b, where m is slope:

8x - 9y = 5

9y = 8x - 5

y = 8/9x - 5/9

m1 = 8/9

9x - 8y = 1

8y = 9x - 1

y = 9/8x - 1/8

m2 = 9/8

So, m1 = 8/9 and m2 = 9/8. They are reciprocal