Need help with this worksheet please. Will give brainliest. Thx

At an art exhibition there are 12 paintings of which 10 are original. a visitor selects a painting at random and before decides to buy he asks the opinion of an expert about the authenticity of the painting. the expert is right in 9 out of 10 cases on average. given that the expert decides the painting is authentic what is the probability it really is? if the expert decides the paining is a copy then the visitor returns it and chooses another one what is the probability that her second choice is an original?