Question

what is the magnification formula?
$\frac{h_i}{h_o}=-\frac{d_i}{d_o}$
$-\frac{h_i}{h_o}-\frac{d_i}{d_o}=1$
$\frac{h_o}{h_i}=-\frac{d_i}{d_o}$
$-\frac{h_i}{h_o}=\frac{d_o}{d_i}$

Explanation:

Magnification is ratio of image - height ($h_i$) to object - height ($h_o$) or negative ratio of image - distance ($d_i$) to object - distance ($d_o$).

Answer:

$\frac{h_i}{h_o}=-\frac{d_i}{d_o}$