You have 85 coins
in nickels, dimes, and quarters with a combined value
of $13.25. there are twice as many quarters as dimes.

There are 25 nickels, 20 dimes and 40 quarters

Step-by-step explanation:

Let

x ----> the number of nickels coins

y ----> the number of dimes coins

z ---> the number of quarters coins

Remember that

we know that

----> equation A

----> equation B

----> equation C

Substitute equation C in equation A and equation B

-----> equation D

-----> equation E

Solve the system of equations D and E by graphing

Remember that the solution of the system is the intersection point both graphs

The solution is the point (25,20)

see the attached figure

Find the value of z

therefore

There are 25 nickels, 20 dimes and 40 quarters

the circle graph is not a function.

step-by-step explanation:

the graph of the circle is not a function.

because for a graph to be a function, each value of x must give one value of y

in the circle, the values of x for -2< x< 2 each give 2 values of y.

hence this is not a function.