Idon’t understand this and need ! !

is true when is false, or when both and are true.

Similarly, is true when is false, or when both and are true.

It seems that you are given that and . According to the truth table given above, these can both be true only when one of is true and the other is false.

On the other hand, is true when either or both of or is true. This is satisfied by the implications in the hypothesis, so must be true.