Answer
Valid by universal modus ponens.
Work Step by Step
Universal modus ponens: $\forall x, $ if $P(x)$ then $Q(x)$.
$P(a)$ for a particular $a$.
$\therefore Q(a)$.
In this case P(x) is: x studies discrete mathematics.
Q(x) is: x is good at logic.
a is Tarik.
