Question

the probability that it will rain tommorrow is 0.85what is the probability that it will not rain tomorrow

Answer 1

P (happening) + P(nothappening) =
0.85 + P (No rain) = 1
P (No rain tomorrow) = 0.15

Answer 2

The probability is maximum 1 which means that the outcome is favourable only.
so
favourable + unfavourable outcome = 1
So, not Rain + Rain = 1
Not rain + 0.85=1
Not rain = 0.15