Aman weighs 78 kg and his two sons weighing 45 kg each were stranded on a river crossing. all they had to cross the river was a small boat, but it could only hold 90 kg. how did the man and his sons cross the river?

While on a train trip, marsha noticed that there were 35 people in her train car. after the next stop, there were only 21 people in her car. if p represents the percent decrease in the number of people in marsha's train car, what is p?