Hi folks I need to work out the probability of a medical side effect arising and I am not sure how to do it.

Background: I have three known medical conditions. No need to know what. According to the research I have done each of the conditions could lead to an increased development of a particular side effect.

The stats are thus.

Condition 1 - 77% of all sufferers will experience side effects
Condition 2 - 33% of all sufferers will experience the side effect
Condition 3 - 40% of all sufferers will experience the side effect

What is the overall probability that I will have of getting this side effect?

Answers please soon as possible as my employer is being an asshole and is treating my time off work due to side effects as a sporadic absence and not linked to any of the medical conditions and I have a meeting with the management tomorrow.