I've put my answers in spoiler tags, I hope you'll try to work them out for yourself

1. This means the chance of A happening. In this case rolling a 1, 2 or 3 of a 6 sided die.

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2. This is the chance of AorB happening and is equal to

P(A U B) = P(A) + P(B) - P(A)P(B)

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3. P(A n B) = P(A)P(B) and it's the chance of both happening

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4. This means the chance of bnothappening and so it is equal to 1-P(B)

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5. This one means the chance of a happening and b not happening:

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