When is the absolute value of a number equal to the number?

Ab+cd-> ad+bc is what kind of reaction

Employers are required to provide guardrail, safety net, or personal fall protection systems to protect workers from falling off unprotected sides/edges of residential roofs that are feet or more above a lower level.

Would you rather know how you die or when you die.i want a pretty good answer that makes sense.or ill report you.lol kidding