16 peeps where at a party. if 21 more came, how are at party

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Afruit stand has to decide what to charge for their produce. they need $10 for 4 apples and 4 oranges. they also need $15 for 6 apples and 6 oranges. we put this information into a system of linear equations. can we find a unique price for an apple and an orange?

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3