What is the slope of the line with equation y=-5x

An architect is designing a water fountain for a park she uses the given function to model the water jet flowing from the fountain nozzles where h(x) gives the height of the water jugs in feet x feet from the starting point h(x)=-1/20x+x+15

Find the value of x for which the lines are parallel.

What is not true about kl and mn? what is mn? (show )