It’s A
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Roughly 39 grams, give or take 1 gram
I hope this helps answer your question. :)
These problems are very hard to do digitally so I would recommend trying to practice these types of problems on paper :)
If the train is moving from Point A to Point B, and this motion we arbitrarily deem "forward", then from the reference point of the train, she will be moving backward. From an external reference point, she will be moving in the same direction as the train, but with a lessened velocity.
FeBr3(aq) + NaOH(aq) = FeOH(s) + NaBr3(aq)