Question 833695
Ten gallons is the difference between {{{(2/3)}}} full and {{{(1/4)}}} full.  That lets you find the capacity of the tank.


Let T = the tank capacity.
{{{(2/3-1/4)T=10}}}
{{{((8-3)/12)T=10}}}
{{{(5/12)T=10}}}
.
Can you do the rest and answer your question?