How do I do this?

Evaluate: f(2) and f(-1) and f(100) for f(x)=-5+35

I expect you have not copied your question properly.

But on the off chance that you didn't, f(x)=30 no matter what the value of x is.

so f(2)=30 and f(-1)=30

I did copy the question correct, thank you for the help :)