Answer:
There are 7 ways in which the formula can be evaluated to False.
Explanation:
In order to solve this problem we will need to build a truth table. In order to build the truth table, we must start by setting the possible truth values combinations. In total there must be 8 rows, which you can see on the first three columns of the attached table.
Next, it is advisable that you divide the formula in little chunks of information that will be easier to evaluate. One column can be (p->q).
Let's evaluate that first column. In general, that column can only be false if p=T -> q=F. Which happens only on the 3dr and 4th rows of the table. The rest of the statements are true.
The next column will be (q->r). The same condition is met here, but this time you take into account the values given on the q and r columns. The false values will happen only on the 2nd and 6th rows. The rest of the rows for that collumn should be true.
Finally you can test for the whole formula. the first, 4th and 5th columns must be true for the formula to be true as well, which will happen only on the first row. The rest of the rows will have at least one false statement which makes the whole row false. So the rest of the rows are false.
(see attached picture for the whole truth table)