Solve n=l+|2-c/f|*h

$$n = l + | \frac { 2 - c } { f } | \times h$$

Solve for c

$$\left\{\begin{matrix}c=\frac{l|f|-n|f|+2h}{h}\text{; }c=\frac{n|f|-l|f|+2h}{h}\text{, }&\left(f\neq 0\text{ and }n\geq l\text{ and }h>0\right)\text{ or }\left(f\neq 0\text{ and }n\leq l\text{ and }h<0\right)\\c=2\text{, }&f\neq 0\text{ and }h\neq 0\text{ and }n=l\\c\in \mathrm{R}\text{, }&n=l\text{ and }h=0\text{ and }f\neq 0\end{matrix}\right.$$

Solve for f

$$\left\{\begin{matrix}f=-\frac{h|2-c|}{n-l}\text{; }f=\frac{h|2-c|}{n-l}\text{, }&\left(n<l\text{ and }c\neq 2\text{ and }h<0\right)\text{ or }\left(n>l\text{ and }c\neq 2\text{ and }h>0\right)\\f\neq 0\text{, }&n=l\text{ and }\left(h=0\text{ or }c=2\right)\end{matrix}\right.$$