A)2,8×2,8^(-3)
=2,8^(1-3)
=2,8^-2
B)(5^(-2))/(5^(-4))
=5^(-2-(-4))
=5^(-2+4)
=5^2
C)((-3,7)^-2))^-5
=-3,7^(-2×(-5))
=-3,7^10
D)7^(-3)/2^(-3)
=(7÷2)^(-3)
=3,5^(-3)
E)((5,6)^-4))^-2
=5,6^(-4×(-2))
=5,6^8
F)10^7×10^(-7)
=10^(7-7)
=10^0
=1
G=(-6)^8×(-6)^-3
=(-6)^(8-3)
=(-6)^5
H)5,3^(-6)×4^(-6)
=(5,3×4)^(-6)
=21,2^(-6)
I=(-4,2)^-5 / (-3)^-5
=(-4,2÷(-3))^(-5)
=1,4^(-5)