Explanation:
g(6) = 3 - 5(6) = 3 - 30 = -27
We know the value of function g at 1 single point, g(6) = -27.
That is not enough to know what function g is.
Since the problem states that g(6) = 3 - 5(6), the problem is trying to guide you into answering that g(x) = 3 - 5x, but this is simply an assumption.