$(2x+1)(5x+2)=(2x+1)(3x-7)$
$⇔10x^2+4x+5x+2=6x^2−14x+3x−7$
$⇔10x^2+9x+2=6x^2−11x−7$
$⇔4x^2+20x+9=0$
$⇔2x(2x+9)+(2x+9)=0$
$⇔(2x+9)(2x+1)=0$
⇔\(\left[ \begin{array}{l}2x+9=0\\x=\dfrac{-9}{2} \end{array} \right.\)
⇔\(\left[ \begin{array}{l}2x+1=0\\x=\dfrac{-1}{2} \end{array} \right.\)