While solving $12x^2-25x+12=0$ by the formula you find $b^2-4ac=49$. The roots are:

$D=625-576=49$, so $x=\frac{25\pm 7}{24}$, giving $\frac{32}{24}=\frac{4}{3}$ and $\frac{18}{24}=\frac{3}{4}$. Both roots are positive because b is negative while a and c are positive. Dividing by $a=12$ instead of $2a=24$ gives $\frac{8}{3}$ and $\frac{3}{2}$.