How many ways can 13 students line up for lunch

If i have one apple and give you the apple, how many apples do i have?

Ammonia molecules have three hydrogen atoms and one nitrogen atom.how many of each atom arein five molecules of ammonia

Write an equation of the line that passes through the point (2, 3) and is perpendicular to the line x = -1. a) y = 1 b) y = 3 c) y = 0 eliminate d) y = -3