Luis bought stock at $66.80. The next day, the price increased $13.85. This new price changed by −2 3 /4 % the following day. What was the final stock price, rounded to the nearest cent? ?

• calculista: we know that
  1) Luis bought stock at ---------------> $66.80
  2) The next day, the price increased $13.85--------> $66.80+$13.85=$80.65
  3) This new price changed by −2 3 /4 % the following day
  2 3/4%----> (2*4+3)/4----> 11/4 %----> 2.75%
  so
  (100%-2.75%)-----> 97.25%
  the final stock price is $80.65*0.9725-----> $78.43
  
  the answer is 
  $78.43