Which of the following is the correct formal definition of the conditional probability P(B|A)?

A survey of drivers recorded whether each driver texted while driving and whether they received a warning last year. The counts from the survey show that $30$ drivers both texted while driving and received a warning, and $120$ drivers received a warning in total. What is the probability that a driver texts while driving, given that they received a warning last year?

A certain disease is present in $2\%$ of a population. A screening test for the disease is positive $85\%$ of the time when the person has the disease and $7\%$ of the time when the person does not have the disease. Let $E$ be the event "the person has the disease" and $F$ be the event "the test is positive." What is the probability that a person actually has the disease given that they test positive?

Bag L contains 4 red and 6 blue marbles; Bag R contains 5 red and 15 blue marbles. A bag is selected with P(L)=2/3 and P(R)=1/3. A drawn marble is red. What is the exact probability it came from Bag L (simplified fraction)?

Algebraically derive Bayes' theorem starting from the conditional probability identity $P\left(B\mid A\right)=P(A\cap B)/P\left(A\right)$ and $P\left(A\mid B\right)=P(A\cap B)/P\left(B\right)$. Which equation correctly shows the derivation of Bayes' formula?