Answer:
3×10^-12 C
Explanation:
The total of the three charges is ...
(-3 +8 +4)×10^-12 C = 9×10^-12 C
Assuming the charge is equally distributed between the balls when they are brought in contact, the charge on each ball will be ...
(9/3)×10^-12 C = 3×10^-12 C
