Ok so basically if an input (x) has more than one output (y) it is NOT a function. One output having more than one input is okay though.
So G) is a function, bc for every x there is just 1 y
H) is not a function
I) is not a function either
Then the 6 below ( i can't read their numbers so they're just gonna be 1-6, top 3 from left to right then the bottom three from left to right)
1. function
2. not a function
3. function
4. function
5. not a function
6. not a function
i might be wrong, but i hope this helps!