How do you fix rust on gutters?

You can scrub off rust with a wire brush, paint the rusty gutters, and caulk holes in the gutters. 

However, these are temporary fixes that only cover up how the gutters look. Rust and other problems will only reappear down the road. 

The best way to address rusted gutters is to have them inspected and repaired accordingly, depending on the degree of damage.