I have some problems similar to this, but in the back of the book it just says answers will vary...

Could someone please break this down to me?

Given events A and B within the sample space S, the following sequence of steps establishes formulas that can be used to compute conditional probabilities. Justify each statement.

a)

b)Therefore,

c) Therefore, P(B|A) = n(A and B)/n(S) over n(A)/n(S)

d)Therefore,

Use the results from above to find each probability in a standard deck of 52 cards.

Like this one for example:

Mr F says: This probability is obviously equal to 1.