Can a fact family be written for this set of numbers 9,9,9​

Which statement accurately explains whether a reflection over the x-axis and a 180° rotation would map figure acb onto itself?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9