She'd be correct if the brothers were twins, but one of them was sent on a spaceship moving really fast, such that he ages at half the rate relative to the brother left on Earth.

But somehow I doubt this is the thought in her head during this video...

Her fault for getting involved with a "morning person".

And states want to remove algebra from high schools because too many kids fail algebra. Sad.

She was thinking algebraically, but incorrectly assuming x and y. So go ahead and remove algebra so dumb people don't apply it incorrectly.

That's cool. Honestly had to stop and think about it for 5 seconds.

We are doomed as a race...

It's great when she gets it.

I agree I thought all humanity was lost for second.