Решение систем уравнений второй степени

Решите задачу:

$\left \{ {{4*(-5)-4=-24} \atop {-5+2*4=b(4-5)}} \right. \\ \left \{ {{-24=-24} \atop {-5+8=-b}} \right. \\ \left \{ {{-24=-24} \atop {3=-b}} \right. \\ \left \{ {{-24=-24} \atop {b=-3}} \right. \\ b=3\\===========================\\ \left \{ {{-0.3*1+0.3=0} \atop {1-6*(-0.3)=b(1-0.3)}} \right. \\ \left \{ {{-0.3+0.3=0} \atop {1+1.8=0.7b}} \right. \\ \left \{ {{0=0} \atop {0.7b=2.8}} \right. \\ \left \{ {{0=0} \atop {b=4}} \right. \\ b=4$