Question 829953
<pre>
The other way to do this problem is to memorize the formula for
the area of a trapezoid:

{{{A}}}{{{""=""}}}{{{((B+b)h)/2}}}

where capital B is one parallel side and small b is the other parallel side
and h is the height:

So we substitute A=162, b=6, h=18 and leave the B unknown to solve for:

{{{162}}}{{{""=""}}}{{{((B+6)(18))/2}}}
  {{{162}}}{{{""=""}}}{{{(B+6)(9)}}}
   {{{162}}}{{{""=""}}}{{{9B+54}}}
    {{{108}}}{{{""=""}}}{{{9B}}}
     {{{12}}}{{{""=""}}}{{{B}}}

Edwin</pre>