# How do you solve for s in v^2= 2as?

Divide both sides with $2 a$ (assuming that $a \ne 0$) hence
${u}^{2} / \left(2 a\right) = \frac{2 a s}{2 a}$
${u}^{2} / \left(2 a\right) = \frac{\cancel{2 a} \cdot s}{\cancel{2 a}}$
$s = {u}^{2} / \left(2 a\right)$