Figure 21-25 shows four identical conducting spheres that are actually well separated from one another. Sphere W (with an initial charge of zero) is touched to sphere A and then they are separated. Next, sphere W is touched to sphere B (with an initial charge of -32e) and then they are separated. Finally, sphere W is touched to sphere C (with an initial charge of + 48e), and then they are separated. The final charge on sphere W is +18e.What was the initial charge on sphere A?
