(x+5)(2x-1)=(2x-3)(x+1)

$(x+5)(2x-1)=(2x-3)(x+1)$
$⇔ (x+5)(2x-1)-(2x-3)(x+1)=0$
$⇔ 2x² - x + 10x - 5 - ( 2x² + 2x -3x - 3 ) = 0 $
$⇔ 2x² + 9x - 5 - 2x² -2x + 3x + 3 = 0 $
$⇔ 10x - 2 = 0 $
$⇔ x = 0,2$

$S = ${ $0,2$ }