Answer
The conclusion: $\therefore \frac{2}{3} + \frac{4}{5} = \frac{(2\cdot 5 +3 \cdot 4)}{3 \cdot 5}$
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: for all real numbers a, b, c, and d, if $b \neq 0$ and $d \neq 0$.
Q(x) is: a/b + c/d = (ad + bc)/bd.
Plug in the particular values for a, b, c, and d (2, 3, 4, 5 respectively) into Q to obtain the conclusion: $\therefore \frac{2}{3} + \frac{4}{5} = \frac{(2\cdot 5 +3 \cdot 4)}{3 \cdot 5}$.
