1. The problem statement, all variables and given/known data A point charge 10 km in the air with a charge of 40 coulombs A point charge 5 km in the air with a charge of -40 coulombs A point chare 2 km in the air with a charge of 10 coulombs -Find the electric potential due to these charges at a point which at a height of 8 km and on the vertical line passing through the charges. 2. Relevant equations kq1/r1 + kq2/r2 3. The attempt at a solution So I summed them up v = k (40C/2000m - 40C/3000m + 10C/6000m) = 7.5E7 My question is, is do I need to convert km to m and was I correct in subtracting the negative 40 coulomb charge from the rest of the positive charges?