<s>[INST] How to rearrange this? Can you please help me to derive the second equation from the first one? I'd really appreciate your help!
$$
-\frac{1}{w-s-d} + \frac{1+r}{1+z} \cdot \frac{1}{(1+r)s+(1+n)d} = 0 \tag{1}
$$
$$
(2 + z)(1 + r)s = (1 + r)(w - d)-(1 + z)(1 + n)d \tag{2}
$$
Many thanks! 
 [/INST] \begin{align}
-\frac{1}{w-s-d}+\frac{1+r}{1+z}\cdot \frac{1}{(1+r)s + (1+n)d} &= 0\\
\frac{1+r}{1+z}\cdot \frac{1}{(1+r)s + (1+n)d}&= \frac{1}{w-s-d}\\
\frac{1}{1+z}\cdot \frac{1}{(1+r)s + (1+n)d}&=\frac{1}{(w-s-d)(1+r)}\\
(1+z)[(1+r)s+(1+n)d] &= (w-s-d)(1+r)\\
(1+z)[(1+r)s+(1+n)d]+s(1+r) &= (w-d)(1+r)\\
(1+z)(1+r)s+s(1+r)&= (w-d)(1+r)-(1+z)(1+n)d\\
(2+z)(1+r)s &= (1+r)(w-d)-(1+z)(1+n)d.
\end{align}
Explanation:
First add $\frac{1}{w-s-d}.$ Secondly divide by $(1+r)$. Then take the inverse. Then add $s(1+r)$. Then subtract $(1+z)(1+n)d$. Lastly, do the final small simplifications.
</s>