A family made a down payment of $55 and borrowed the balance on a set of encyclopedias that cost $400. The balance with interest was paid in 23 monthly payments of $16 each and a final payment of $9. The amount of interest paid was what percent of the amount borrowed?
Choose one.
A) 6%  B) 8%  C) 7.7%  D) 10%  E) 5%
borrowings = 400-50= 
<gadget id="calculator">400-50</gadget>
<output>350</output>
350   total pmt= 23x16 + 9 = 377   so int = 377 - 350= 
<gadget id="calculator">377 - 350</gadget>
<output>27</output>
27   interest in terms of borrowing= 27/350 = 7.7%   Answer is 7.7%
<result>C</result>
A family made a down payment of $55 and borrowed the balance on a set of encyclopedias that cost $400. The balance with interest was paid in 23 monthly payments of $16 each and a final payment of $9. The amount of interest paid was what percent of the amount borrowed?