How can i work out this probability question?

Hi

Suppose i have 3 coins in a bag:two are ordinary coins,one has head on both sides.

i) i take a coin out of my bag at random and toss it.what is the probability it comes down heads?

ii)Suppose i take a coin out of my bag randomly,toss it,and it comes down heads.What is the probability that the other side is a head?

iii)What is the probability that if i toss the same coin a second time i will get another head?

Thanks i really appreciate if someone could give me an explanation of how to get there