a) 2x-y=2;
2x^2-xy=6;
y=2x-2
2x^2-x(2x-2) =6;
2x^2-2x^2+2x=6;
2x=6;
x=3;
y=2*3-2=4.
Ответ: x=3
y=4
(b+d)/(4b+4d)-(b+2d)/(2d-5b)=1/4-(b+2d)/(2d-5b)=(2d-5b-b-2d)/4(2d-5b)=-3b/2(2d-5b)