Why is this he correct? [closed]

Here is the question:

"A spring stretches 0.4m when a 2kg mass is hung from it. The spring is stretched an additional 0.2m from its equilibrium point and is released. Determine: The Max Acceleration"

The formula for Max Acceleration is: kA/m where: k=spring constant A = Amplitude m = mass

The Spring Constant is 49N which I found and is correct. Now my question is: Why is the Amplitude 0.2m? The video I am watching:Simple Harmonic Motion at point: 46:16, he says the amplitude is 0.2m but wouldn't it be 0.6m since it said additionally in the problem or did we just create a new equilibrium out of nowhere? Thanks! -Guy who has a final tomorrow and is learning an entire semester in 2nights

closed as off-topic by ZeroTheHero, Buzz, Kyle Kanos, Jon Custer, M. EnnsDec 19 '18 at 3:57

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• When I'm in a sufficiently abstract mood I like to think about it like this: $\text{a 2-nominal} + \text{a 1-nomial}$ is still a 2-nomial and it still has the same quadratic coefficient. – dmckee Dec 18 '18 at 3:50