Not necessarily, the more correct definition is opposite reciprocal slopes.
The example used is how horizontal and vertical lines are parallel. Horizontal lines have a slope of 0, also written as 0/1. However, vertical lines have an undefined slope, which isn't necessarily negative. It has a slope of 1/0, which is undefined. In this case, the reciprocal isn't negative.
In all other cases (1 and -1, 2 and -1/2, etc.) yes, the perpendicular pairs are negative and reciprocal.
It should take 1.75 minutes to run it 1.5 times
that is 1 and 3/4 minutes
5(n+6)=48
5n+30=48
5n=18
n=18/5
The answer is
3^66483360316461674016