How much of the circle is shaded 1/7 + 1/2

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

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Bernice paid $162 in interest on a loan of $1800 borrowed at 6%. how long did it take her to pay the loan off?