Work done by external force vs electric field on a point charge

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collegeconfid
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Homework Statement


How much work is required to bring a 3 C point charge from infinity to a point X. The change in electric potential from infinity to point X is -6 V.


Homework Equations


-QV=W



The Attempt at a Solution


The answer is -18 J. MY confusion is whether this is the work done by the electric field or an external force? My guess is it is the work done by an external force, however my book says different? Or maybe I'm misinterpreting the question can you confirm that it's an external force?
 

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Assuming the charge starts and ends its journey at rest, it is the work you have to do to overcome the force of the electric field in bringing that charge to X.