Question 1038886
p(s) = .12
p(o) = .16
p(s and o) = .02


p(s or o) = p(s) + p(o) - p(s and o).


that would make p(s or o) = .12 + .16 - .02 = .28 - .02 = .26.


the assumption is that p(s and o) is being double counted because it's included in p(s) and it's included in p(o).


that's why you have to subtract one occurrence of it.