Where do I even start?

I am having a very hard time with these kinds of questions, and just visualizing them is difficult for me. Can anyone give me any hints or advice on how to do something like this? I don't understand the class examples, and the book doesn't have many examples. Thanks to anyone who can help.

According to the latest US Forest survey, 42% of the state is forested.

a) Suppose this estimate is correct. If you randomly select 20 pixels from a map of the state, how many would you expect to be forested?

b) Suppose you randomly select 10 pixels and 7 are forested. What is the probability of this result if the estimate is correct?

c) What is the probability of observing 7 or more forested pixels in a random sample of 10 if the estimate is correct?

Again, thanks to anyone who can help me understand this kind of concept.