The formula for Coulomb's law is $F = k \frac{|q_1q_2|}{r^2}$, where $k$ is Coulomb's constant, $q_1$ and $q_2$ are the charges, and $r$ is the distance between the charges.
So, the force on A by B is given by:
\[F_{AB} = k \frac{|q_Aq_B|}{r_{AB}^2} = 8.99
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