6. [10 points] John and Jim are two brothers and they are going to the same school. According to the past experience, on each morning, the probability that John is late to school is 25%, the probability that Jim is late to school is 18%, and the probability that they are both late is 10% (a) In a given morning, what is the probability that at least one of the brothers is late to school? (b) In a given moming, what is the probability that Jim is present on time?