-20 because when you turn the fraction into a decimal which would be 2.5 then you multiply it by -8 it =-20
Depending on how far the source where the signal is coming from is, radio waves travel at the speed of light. If the civilization lives in a star system that is 20 light years away from us, the signal would take 20 light years to reach us.
(1 light year = 1 normal year but traveling or moving at the speed of light).
Answer:
I think it's A ,the citizens elect both president and members of the legislature