Chapter 7, Problem 45PC

Two point charges, each with $0.1\text{C}$ of charge, are $0.1\text{m}$ apart. Given that $k$ is $9\times {10}^9\text{N}\cdot {\text{m}}^2/{\text{C}}^2$ (the proportionality constant for Coulomb's law), show that the force between the charges is $9\times {10}^9\text{N}$.