the average marks of a class of 20 students is 40 and that of another class of 50 students is 60 . find the average marks of all the students ?
"sum of the marks for the class of 20 students = 20 * 40 = 800 sum of the marks for the class of 50 students = 50 * 60 = 3000 sum of the marks for the class of 70 students = 800 + 3000 = 3800 average marks of all the students = 3800 / 70 = 54.28 answer : b"
divide(add(multiply(20, 40), multiply(50, 60)), add(20, 50))