Tell whether or not the pairing is a function

Input Output
9 0
8 2
7 4
7 6

I think it is I'm just not sure it's the 2 sevens that
Are really bothering me if someone can help id appreciate it.

It's a function if for every x value there is one and only one "y" value that you could have. It's OK if more than one x value shares the same y value, but you can't have 2 or more y values for one single x value.