X axis and Y axis

Question 1

X axis?

Answer 1

(x,y) —-> (x,-y)

Question 2

Y axis?

Answer 2

(x,y) —> (-x,y)

Question 3

y=x

Answer 3

(x,y) —-> (y,x)

Question 4

y=-x

Answer 4

(x,y) —-> (-x,-y)