Thank you for the opportunity to help you with your question!
If Olive company has a probability of p to get the job and Base company is the only other company than their probability is 1 - p. This is because all possibilities must add up to 1. So, Olive plus Base must equal 1 or p + (1 - p) = p + 1 - p = 1. Probability p is unknown it is just a variable.
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