If 15 students in a class average 75% on an exam and 10 students average 90% on the same exam, what is the average in percent for all 25 students? Choose the correct answer.
A) 80%  B) 81%  C) 82%  D) 83%  E) 84%
(15*75 + 10*90) / 25= 
<gadget id="calculator">(15*75 + 10*90) / 25</gadget>
<output>81</output>
81%   The answer is 81%.
<result>B</result>
If 15 students in a class average 75% on an exam and 10 students average 90% on the same exam, what is the average in percent for all 25 students?