the average of 30 results is 20 and the average of other 20 results is 30 . what is the average of all the results ?
"answer sum of 50 result = sum of 30 result + sum of 20 result . = 30 x 20 + 20 x 30 = 1200 correct option : a"
divide(add(multiply(30, 20), multiply(20, 30)), add(30, 20))