ED Griffiths "World Line" Problem: Solution to p.506, prob. 12.22

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In the book of ED of Griffiths, p.506, prob. 12.22, I don't understand why the solution manual says that one can say she arrived at B before she left A?
Any help would be appreciated.
 
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rbwang1225 said:
In the book of ED of Griffiths, p.506, prob. 12.22, I don't understand why the solution manual says that one can say she arrived at B before she left A?
Any help would be appreciated.

The question asks:

Show, using a world line diagram, if it's possible for her to arrive before she set out if she can travel at a velocity greater than c.
 

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