Of the Delegates at a Convention, 60% Attended the Breakfast

Of the delegates at a convention, 60% attended the breakfast forum, 70% attended the dinner speech, and 40% attended both events.
a. If a randomly selected delegate is known to have attended the dinner speech, what is the probability he or she also attended the breakfast forum?
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b. What is the probability that a randomly selected delegate either attended the breakfast forum, or attended the dinner speech, or attended both?
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