remember
(a+b+c)/d=a/d+b/d+c/d
I would first leave the 2 way outside because
2a/b=2(a/b)
so simplify the a/b bit first
(wl+hl+hw)/whl=
wl/whl+hl/whl+hw/whl=
1/h+1/w+1/l
then the final 2
2(1/h+1/w+1/l)
2/h+2/w+2/l is simplified
[tex] \frac{2}{h} +\frac{2}{w}+ \frac{2}{l} [/tex]
