# What is the force, in terms of Coulomb's constant, between two electrical charges of -105 C and -15 C that are 15 m  apart?

${F}_{c} = 7 \cdot k \text{ you can write " 9.10^9 " instead of k}$
$\text{force between two charges is given by :} {F}_{c} = \frac{k \cdot {q}_{1} \cdot {q}_{2}}{d} ^ 2$
${F}_{c} = \frac{k \left(- 105\right) \cdot \left(- 15\right)}{15} ^ 2$
${F}_{c} = \frac{k \cdot 105 \cdot \cancel{15}}{\cancel{15}} ^ 2$
${F}_{c} = \frac{k \cdot 105}{15}$
${F}_{c} = 7 \cdot k \text{ you can write " 9.10^9 " instead of k}$