To fill in column 4 in the truth table below, we compare column 1 with column 2, recognizing that column 1 is the antecedent for this conditional statement, so the only time column 4 can be false is when column 1 is true while column 2 is false.

To fill in column 5 we compare column 3 with column 2, using disjunction. The only time this "or" statement can be false is when columns 3 and 2 are both false.

The truth table shows that the statements in columns 4 and 5 are equivalent.