For f(x) = 5x -4, the slope is 5 and the y-intercept is 4.

For any two cotangent lines, we know:

1. The slopes are opposites. Thus, the slope of the second line must be -5.

2. The sum of the y-intercepts is 1. Thus 4 + b = 1. The y-intercept of the second line is -3.

So, the second cotangent line is represented by the function g(x) = -5x - 3. A graph of f, g, and fg is below.


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