Peggy had four times as many quarters as nickels. she had $2.10 in all. how many nickels and how many quarters did she have?

if the variable n represents the number of nickels, then which of the following expressions represents the number of quarters?

the possible answers are:
n/4
n
4n
n + 4

For the answer to the question above, 
and we are told that there are "four times as many quarters as nickels"
this translates to
q = 4n

0.05n + 0.25q = 2.10
and
q = 4n
are your two equations that could be used to solve this problem

if you would like to know how many nickels and how many quarters there are, plug in q = 4n into the first equation and get
0.05n + 0.25(4n) = 2.10
then I would stop here
because I didn't see the choices. So the answer is 4n