Two metal spheres, one carrying a 8.0- C charge and the other carrying a -18-

Two metal spheres, one carrying a 8.0-μC charge and the other carrying a -18-μC charge, are initially 100 mm apart. They are brought in contact with each other and then moved back to their original positions. What is the numerical value of the ratio FEi/FEf, where FEi is the magnitude of the electric force between the spheres before they are brought in contact and FEf is the magnitude of that force after they are brought together and then moved back to their initial positions?