Susannah purchased ski equipment for $978 using a six-month deferred payment plan. The interest rate after the introductory period is 21.45%. A down payment of $150 is required as well as a minimum monthly payment of $75. What is the balance at the beginning of the seventh month if only the minimum payment is made during the introductory period?

A.$470.87

B.$920.87

C.$845.87

D.$487.69

My answer is $487.69

1 answer

balance financed = 978-150 = 828
monthly rate = .2145/12 = .017875

balance at end of 6 month if no payment had been made
= 828(1.017875)^6
= 920.87

amount of the 6 payments at that time
= 75( 1.017875^6 - 1)/.017875
= 470.60

balance owing at that time = 920.87 - 470.60 = 450.27

None of the answers match my solution.
Answers B and C aren't even logical.
How did you get 487.69 ?