4/6 can reduce to 2/3. (divide each by 2)
14/21 can reduce to 2/3 by dividing the nume/denominator by 7.
in this case, they are proportional.
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.
You would write it like this:
1/2q+8
3(x-9)
when you distribute the equation you get
3(x)-3(9) which is the last answer