THIS question uses Bayes Rule and I have ABSOLUTELY NO IDEA HOW TO SOLVE IT so if you could provide a step by step that'd be great

On the TV show Iron Chef, the weekly challenger must choose one of the three Iron Chefs (Michiba, Sakai, and Chen) to battle. Based on the data on Wikipedia's Iron Chef page, suppose that if the challenger selects Michiba, there is only a 13% probability they will be able to defeat him. For Sakai and Chen, suppose this probability is 18% and 25% respectively. Since the challenger specializes in Japanese cuisine, you believe there is a 50% probability they will challenge Michiba, a 25% probability they will challenge Sakai, and a 25% probability they will challenge Chen.
Here is part 1
What is the probability the challenger selected Sakai, given that the challenger is known to have won?
Part 2
What is the probability the challenger selected Chen, given that the challenger is known to have won?