Tìm x biết: ( 2x + 3 ) ( x - 4 ) + ( x - 5 ) ( x - 2 ) = ( 3x - 5 ) ( x - 4 ); ( 8x - 3 ) ( 3x + 2 ) - ( 4x + 7 ) ( x + 4) = ( 2x + 1 ) ( 5x - 1 )