Answer:$78
Explanation:
The two events,i.e request for full fare and the request for discounted fare ar mutually exclusive ,i.e if one happens the other cannot and vice versa .
The representation via set diagram will show a disjointed subset while P(AnB)^° is 1- (P(A)+P(B))=0.1.
Where A is the probability of full fare request while B is the probability of discounted request.
Probability (AUB)=P(A)+ P(B)=0.5×100+0.4×70=78.