Person A speaks the truth in 80% of cases, so A speaks the truth with probability 54 and lies with probability 51.
Person B speaks the truth in 75% of cases, so B speaks the truth with probability 43 and lies with probability 41.
Two people contradict each other when one tells the truth and the other lies.
A tells the truth and B lies:
Probability =54×41
=204
=51
A lies and B tells the truth:
Probability =51×43
=203
Total probability of contradiction:
=51+203
=204+203
=207
Therefore, the probability that they contradict each other is 207.