Помогите решить номер 744

А) $(2y-1)(2y+1)-y(4y+3)+5y=0$
   $4 y^{2} +2y-2y-1-4 y^{2} -3y+5y=0$
   $2y-1=0$
   $2y=1$
$y= \frac{1}{2} =0.5$
б) $9m+8m(5-2m)=9 m^{2} -(5m+7)(5m-7)$
   $9m+8m(5-2m)-9 m^{2}+(5m+7)(5m-7)=0$
   $9m+40m-16 m^{2} -9 m^{2} +25 m^{2} -35m+35m-49=0$
   $49m=49$
   $m= \frac{49}{49} =1$
в) $4x(x-1)-8=(1+2x)(2x-1)-6x$
   $4x(x-1)-8+6x-(1+2x)(2x-1)=0$
   $4 x^{2} -4x-8+6x-2x+1-4 x^{2} +2x=0$
   $2x-7=0$
   $2x=7$
   $x= \frac{7}{2} =3 \frac{1}{2}$
г) $-5y+(3y+4)(3y-4)=(4y-3)(3+4y)-7 y^{2}$
$-5y+(3y+4)(3y-4)+7 y^{2} -(4y-3)(3+4y)=0$
$-5y+9 y^{2} -12y+12y-16+7 y^{2} -12y-16 y^{2} +9+12y=0$
$-5y-5=0$
$-5y=5$
$y=- \frac{5}{5} =-1$