Please help. 2 years ago, age of brother was 3 times less than sister's age. this year his age is just 2 times less than his sister's. how old is brother? how old is sister?

Use the normal approximation to the binomial distribution to answer this question. fifteen percent of all students at a large university are absent on mondays. if a random sample of 12 names is called on a monday, what is the probability that four students are absent?

To describe a sequence of transformations that maps triangle abc onto triangle a"b"c", a student starts with a reflection over the x-axis.how should the student complete the sequence of transformations to map triangle abc onto triangle a"b"c"? plz

What are “like terms”? why can we only add like terms?