Answer
The conclusion is: $\therefore$ 1/0 is not an irrational number.
Work Step by Step
Universal modus tollens: $\forall x,$ if $P(x)$ then $Q(x).$
~$Q(a)$, for a particular a,
$\therefore$ ~$P(a).$
In this case P(x) is: if x is an irrational number.
Q(x) is: x is a real number.
a is 1/0.
Therefore ~P(a) is: 1/0 is not an irrational number.
