Which table does not represent y as a function of x

Question

X Y
-5. -5
-2. 0
-5 5
-2 10

X. Y
-5. 5
0. 0
2 -2
4 -4

X. Y
-5. -15
-2. -6
5. 15
8. 24

Answer 1

The third table does not represent y as a function of x because the x-value -5 has two different y-values.