Mathematical logical Solution:

log [1/(10^10)] = -10 log(10) = -10 ->A

log [1/(10^20)] = -20 log(10) = -20 ->B

Now,

So, LHS: A + 3B + 80 + 90

=> -10 + 3(-20) + 80 + 90

=> 100 -> RHS

Hence proved! ( No negative numbers though)

Hence, A is log[1/(10^10)] and B is log[1/(10^20)]