Help please. Thankyou

The damage in a structure after an earthquake can be classified as either none, light, or heavy. For a new undamaged structure, the probabilities that it will suffer light and heavy damages after an earthquake are 25% and 10%, respectively. However, for an old structure with light damage from a previous earthquake, its probability of getting heavy damage during the next earthquake is 60%. (a) For a new structure, what is the probability that it will be heavily damaged after two earthquakes? Assume no repairs were done after the first earthquake. (b) If the structure is heavily damaged after two earthquakes, what is the probability that the structure was either undamaged or with light damage before the second earthquake