It takes 2.5 μJ of work to move a 16 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?

Express your answer using two significant figures.

The potential energy is equal to negative of the work done on a charge to move from point 1 to point 2.

Then in first case, the potential difference between A and B, V_B - V_A = W/q = 2.5*10^-6/(16*10^-9) = 156.25 V

In the second case, the potential difference between B and C = V_B-V_C = -6*10^-6/(16*10^-9) = -375 V

hence subtracting 1 from 2,

V_C-V_A = 375+156.25 = 531.25 V