( ( a - 5 ) / ( ab - a^2 ) ) - ( ( 5 - b ) / ( ab - b^2 )) = ( ( a - 5 ) / ( a( b - a )) - ( ( 5 - b ) / ( b( a - b )) = ( ( a - 5 ) / ( - a ( a - b )) - ( ( 5 - b ) /( b ( a - b )) = ( b( a - 5 ) - ( - a( 5 - b )) / ( - ab( a - 5 )) = ( ab - 5b - ( - 5a + ab )) /( - ab ( a - 5 )) = ( ab - 5b + 5a - ab ) / ( - ab ( a - 5 )) = ( 5a - 5b ) / ( ab ( a - 5 ))