Simplify the following into the form $a^b$ab:

$\left(6^7\right)^{-3}$(67)−3

$\left(6^{-5}\right)^4$(6−5)4

Evaluate $\left(5^{-9}\right)^0$(5−9)0.

Evaluate $\left(7^0\right)^{-6}$(70)−6.