Okay so you're trying to find the unit rate of 720yds/4min. If you divide 720 by 4 you will have the unit rate as 180yds/1 min or 60 sec then if you divide 180 and 60 by 4 again you will get the answer of 45yds/15sec.
It is possible to have a triangle with those lengths
They have the same absolute value because all opposites have the same absolut value because they both are the same distance from zero
No beacuse 1/4 would be less that 1/2 it's common sense