L:y=x+3
(1)
M(a,b)
L^(x,y)
xL+xL^=2a,xL=2a-xL^=2a-x
yL+yL^=2b,yL=2b-yL^=2b-y
yL=xL+3
2b-y=2a-x+3
y=x+2b-2a-3
(2)
x-y-2=0
y=x-2
3-(-2)=5=8-3
y=x+8