Answer:
She will be charged $180 once lets the account go past 6 months before making a payment.
Step-by-step explanation:
This is a simple interest problem.
The simple interest formula is given by:

In which E is the amount of interest earned, P is the principal(the initial amount of money), I is the interest rate(yearly, as a decimal) and t is the time.
After t years, the total amount of money is:

In this question:
If she pays within 6 months, she is not charged any interest.
However, if after 6 months she has not paid the balance, she is charged 20% interest for this period.
Barbara financed a new bedroom set at the furniture store for $1,800.
This means that 
20 percent interest
This means that 
How much interest will she be charged once she lets the account go past 6 months?
6 months is half a year, so this is E when 



She will be charged $180 once lets the account go past 6 months before making a payment.
Answer:
A.
No
B.
Yes
C.
Yes
Step-by-step explanation:
This would be displayed as
3x/5