What is the relation between molarity and molality? Is the following equation correct:

$$m = \frac{1000 \times M}{M \times M_b - 1000 \times d},$$

where $M$ - molarity, $m$ - molality, $d$ -density of solution, $M_b$ - molar mass of solute?
$$m = \frac{M}{\rho - (M \times wt. of solute)}$$

$m=$molality

$M=$Molarity

$\rho=$density

all quantities in S.I. units