Question 984509
Ratio is made of 8+5+7=20 parts.


{{{900=(8/20)*f]]],  some factor f.
{{{900=(4/5)*f}}}
{{{f=900*5/4}}}
{{{f=1125}}}


Width is  {{{(5/20)*1125=(1/4)*1125=highlight(281.25)}}}


Height is  {{{(7/20)*1125=highlight(393.75)}}}


Volume is  {{{(900)*(281.25)*(393.75)*cm^3}}}.