The events are mutually exclusive, because your primary method can't be both a driving a car or taking a bus.
Since they are exclusive, the probability of the "or" clause is the sum of the probabilities:
[tex]P(A\lor B)=P(A)+P(B)=0.48+0.32=0.8[/tex]
Since a person primarily takes a bus with probability 0.32, the opposite happens with probability
[tex]1-P(B) = 1-0.32=0.68[/tex]