Let "R" be distance between Sphere centers. Then vector Force "\(\displaystyle{F}_{{1}}\)" on Sphere #1 is equal & opposite to vector Force "\(\displaystyle{F}_{{2}}\)" on Sphere #2:

\(\displaystyle{F}_{{1}}=-{F}_{{2}}\)

The Spheres REPEL each otherbecause they each contain the SAME-SIGN charge. Thus, using Coulomb's Law:

\(\displaystyle\text{Magnitude }\ {F}_{{1}}=\text{Magnitude }\ {F}_{{2}}={\frac{{{1}}}{{{4}\cdot\pi\cdot\epsilon_{{0}}}}}\cdot{Q}\cdot{\frac{{{3}\cdot{Q}}}{{{R}^{{2}}}}}\)

Direction \(\displaystyle{F}_{{1}}\)=OPPOSITE Direction \(\displaystyle{F}_{{2}}\)

{Sphere #1 &Sphere #2 REPEL Each Other}