The question is missing, however, I guess the problem is asking for the value of the force acting between the two balls.
The Coulomb force between the two balls is:
[tex]F= k_e \frac{ q_1 q_2}{r^2} [/tex]
where [tex]k_e=8.99\cdot10^9~N m^2 C^{-2}[/tex] is the Coulomb's constant, [tex]q_1=q_2=29~nC=29\cdot 10^{-9}~C[/tex] is the intensity of the two charges, and [tex]r=5.5~cm=0.055~m[/tex] is the distance between them.
Substituting these numbers into the equation, we get
[tex]F=2.5~10^{-3}~N[/tex]
The force is repulsive, because the charges have same sign and so they repel each other.
