The following table is a function, but its inverse is not a function.
 $x$ $f(x)$ $2$ $7$ $5$ $3$ $6$ $9$ $10$ $7$
There is an output value of $f$ that is causing the inverse $f^{-1}$ to not be a function.
Which output value is the problem?
How is that output value of $f$ causing the inverse to not be a function?

Hint: