Question 861491
You wrote your constant wrong but other than that your solution is correct.
{{{2LW+2LH+2WH=1440}}}
{{{LW+LH+WH=720}}}
{{{(2W)W+2W(6W)+W(6W)=720}}}
{{{2W^2+12W^2+6W^2=720}}}
{{{20W^2=720}}}
{{{W^2=36}}}
{{{W=6}}}
{{{L=2(6)=12}}}
{{{H=6(6)=36}}}
{{{V=L*W*H=12*6*36=2592}}}{{{cm^3}}}