the average of 55 results is 28 and the average of other 28 results is 55 . what is the average of all the results ?
"answer sum of 83 result = sum of 55 result + sum of 28 result . = 30 x 20 + 20 x 30 = 3080 correct option : a"
divide(add(multiply(55, 28), multiply(28, 55)), add(55, 28))