Answer:
-[tex]10^{13}[/tex]
Step-by-step explanation:
Numbers with the same base multiplying with each other will have their expoenent add up.
In this case, both number has a base of -10, so we're allow to group them and add up their exponents.
[tex](-10)^8(-10)^5=(-10)^{8+5}=(-10)^{13}[/tex]
