The temperature of a mixture is decreasing by 5∘C every hour. When it was first mixed, its temperature was recorded at −20∘C.
Which answer correctly represents the temperature of the mixture over time?

f(x)=−20x−5
That is incorrect.
f(x)=−5x−20
f(x)=−20x+5
f(x)=5x+20
f(x)=−15x