if 15 students in a class average 73 % on an exam and 10 students average 88 % on the same exam , what is the average in percent for all 25 students ?
"( 15 * 73 + 10 * 88 ) / 25 = 79 % the answer is c ."
divide(add(multiply(15, 73), multiply(10, 88)), 25)