Work of charge and potential difference-please help:)

Question

It takes 4.0 μJ of work to move a 11 nC charge from point A to B. It takes -6.0 μJ of work to move the charge from C to B.

What is the potential difference VC−VA?

Answer 1

The differencce VC - VA is defined as the work necessary to bring 1C charge

from A to C.

And it does not matter along what path the charge is moved.

So we can take the path A -> B -> C.

Along that path it takes 10.0 μJ to move 11 nC.

Therefore

VC - VA = 10.0μJ/11nC = 909.1 V