if 15 students in a class average 70 % on an exam and 10 students average 95 % on the same exam , what is the average in percent for all 25 students ?
"( 15 * 70 + 10 * 95 ) / 25 = 80 % the answer is d ."
divide(add(multiply(15, 70), multiply(10, 95)), 25)