Answer: The expression will be 
Step-by-step explanation: Frank has to pay $50 as the registration fee. This amount is compulsory to be paid
Step 1: Dues for $12 months
Let the due to be paid every month be $x, so dues to be paid for 12 months will be 12x
Step 2: Expression for the average monthly cost for x-month will be
Expression: 
Total cost = 50 + 12x
Expression: 
For this case, we can model the problem as a triangle with a right angle.
Where,
x, y: lengths of the sides of the triangle
d: hypotenuse of the triangle
We then have the following relationship:

Clearing d we have:
Answer:
A functions that would best model the situation above is:
D square root
This is a problem of guess and check; there's no easier way to do it.But in this case you must have an odd number of nickels to make the 5 cents, so your answer is 9 nickels.you can check this by multiplying each one by .05:
9*.05=.45
the rest of the coins left, are 8 of them, and their dimes.
.10*8=.80
.80+.45= 1.25