the average marks of a class of 30 students is 50 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 30 students = 30 * 50 = 1500 sum of the marks for the class of 50 students = 50 * 60 = 3000 sum of the marks for the class of 80 students = 1500 + 3000 = 4500 average marks of all the students = 4500 / 80 = 56.25 answer : a"
divide(add(multiply(30, 50), multiply(50, 60)), add(30, 50))