In the future, would you please post just one or two problems at a time.  Be fair to others who also want help.
#5:     (-4)^8/(-4)^4 can be expressed more clearly as     (-4)^8
                                                                                         ---------
                                                                                           (-4^4)
and this can be reduced to (-4)^4    by subtracting the exponent 4 from the 
                                                         exponent 8.
furthermore, because of the even exponent, (-4)^4 can be written as 4^4.
Note that 4^4 = (4^2)^2 = 16^2 = 256 (answer)