Three years ago, the average age of A and B was 18 years. With C joining them now, the average age of all three becomes 22 years. How old is C now (in years)?

What is the average number of students in B.Tech (220), M.Tech (140), and B.A (4344) courses together?

A class has two sections A and B, which have 36 and 44 students respectively. If the average weight of section A is 40 kg and that of section B is 35 kg, find the average weight of the whole class.