To solve this question, we will apply the knowledge of exponents and indices
The values have the same bases (7) but different powers and they are separated by a multiplication sign.
So we can use the law:
[tex]a^{x\text{ }}\text{ x a}^{y\text{ }}=a^{x\text{ + y}}[/tex]so that
[tex]7^{-6}\text{ x 7}^3=7^{-6\text{ + 3}}[/tex]on simplifying will give
[tex]7^{-3}[/tex]=>
[tex]7^{-3}\text{ =}\frac{1}{7^3}[/tex]