Can someone solve it please I need it now

Consider the function f(x)=-5x+3 what is f(-2)

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?

Describe how you can act financially responsible.