Помогите сократить дробь:

Решите задачу:

$\frac{12xy-4 x^{2} -5 y^{2} }{2 x^{2} -15 y^{2}+xy } = \frac{-4(x-0,5y)(x-2.5y) }{2(x-2.5y)(x+3y)} = \frac{-2(x-0,5y)(x-2.5y) }{(x-2.5y)(x+3y)} = \frac{-2(x-0,5y) }{(x+3y)} =$ $- \frac{2x-y}{x+3y}$

$12xy-4 x^{2} -5 y^{2}=0$
$-4 x^{2}+12xy -5 y^{2}=0$
$a=-4$
$b=12y$
$c=-5y^2$
$D=(12y)^2-4*(-4)*(-5y)=144y^2-80y^2=64y^2$
$x_1= \frac{-12y+8y}{-8} =0.5y$
$x_2= \frac{-12y-8y}{-8} =2.5y$
$-4x^2+12xy-5y^2=-4(x-0.5y)(x-2.5y)$

$2 x^{2} -15 y^{2}+xy=0$
$2x^2+xy-15y^2=0$
$a=2$
$b=y$
$c=-15y^2$
$D=y^2-4*2*(-15y^2)=121y^2$
$x_1= \frac{-y+11y}{4} =2.5y$
$x_2= \frac{-y-11y}{4} =-3y$
$2x^2+xy-15y^2=2(x-2.5y)(x+3y)$