Question 946612
Area of remaining roof = 
{{{ ( 10x + 89 )*( 7x + 7 ) - ( x + 5 )*( 3x + 3 ) }}}
{{{ 7*( 10x + 89 )*( x + 1 ) - 3*( x + 5 )*( x + 1 ) }}}
Factor out {{{ x + 1 }}}
{{{ ( x + 1 )*( 7*( 10x + 89 ) - 3*( x + 5 ) ) }}}
{{{ ( x + 1 )*( 70x + 623  - 3x - 15 ) }}}
{{{ ( x + 1 )*( 67x + 608 ) }}}
{{{ 67x^2 + 67x + 608x + 608 }}}
{{{ 67x^2 + 675x + 608 }}}