Just want someone to make sure this answer is correct

Is the following relation a function? x y 1 4 −1 −2 3 10 5 16 yes no

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

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?