islambay13 A)
x=2-y
xy=-15

(2-y)y=-15

y=5
y=-3

x=2-5
x=2-(-3)

x=-3
x=5

(x1;y1)=(-3;5)
(x2;y2)=(5;-3)

б)
y=-1-2x
x^2+2y=3

x^2+2(-1-2x)=3

x=5
x=-1

y=-1-2*5
y=-1-2*(-1)

y=-11
y=1

(x1;y1)= (5;-11)
(x2;y2)=(-1;1)