One dice rolled twice

What is the probability of one dice rolled twice that will result in exactly one three being rolled?

Also what is the probability of at least one three being rolled (one dice rolled twice)? I have the answers, I just need to understand it…
The answer for exactly one three comes up is 5/18 and at least one three comes up is 11/36. How did they get 5/18?

Question posted by: atukomeyer