Question

A^2 - b^2 / 4 a=5 b=3

Answer 1

Assming you mean $\frac{a^2-b^2}{4}$

so

$\frac{a^2-b^2}{4}$
a=5
b=3

$\frac{5^2-3^2}{4}$
$\frac{25-9}{4}$
$\frac{15}{4}$