Answer
False.
Work Step by Step
We are given that $y=f(x)$, which means that y is a function of x.
Also, we know that when x=7, y=f(7)=50. However, this is not the same as saying that when x=50, y=7. We are not given the value of f(50), so we do not what y equals when x=50.
This statement is false.
