My question says,
On Wednesday the weather forecast for Thursday was 60% chance of rain and a 35% chance of rain on Friday. If there is a 20% chance of rain on both Thursday and Friday, what is the probability that there will be rain on Thursday or Friday?
I have to use the Principle of Inclusion and Exclusion to determine the probability of events occuring at the same time, but I'm not sure how to. Please help! Any and all suggestions and help is appreciated!