Aweather station in a major city in the northwest kept data about the weather conditions over the past year. the probabilities are displayed in the table below:

hot mild cold
sunny 0.15 0.30 0.10
cloudy 0.10 0.25 0.10

if a random day is chosen from this data, what is the probability that the day was hot or sunny?

It is important to note that all the information's required are already given in the question

Probability that a day will be hot = 0.15 + 0.10
                                                   = 0.25
Probability that a day will be sunny = 0.15 + 0.30 + 0.10
                                                        = 0.55
Adding the above two probabilities, we get = 0.25 + 0.55
                                                                     = 0.80
Now
Probability that a day will be both hot and sunny = 0.15
So
Probability that a day was hot or sunny = 0.80 - 0.15
                                                               = 0.65
I hope the procedure is clear enough for you to understand.