Question 1062161
The 3-dimensional box will be {{{ 5*(w-10)*(w+17-10) = 300 in^3 }}}

{{{ (w-10)(w+7) = 60 }}}
{{{  w^2+7w-10w-70 = 60 }}}
{{{  w^2-3w-130 = 0 }}}
{{{  (w-13)(w+10) = 0 }}}
{{{ w=13 }}} or {{{ w=-10 }}}

Discard the negative answer.

w = 13  —> l = 13+17 = 30
-
Ans:  width is 13in,  length is 30in
—
Check:
       (13-10)*(30-10)(5) = (3)(20)(5) = 300  (ok)