Class a had 40 students with an average of 78. class b had 25 students with an average of 72. what is the average for these two classes together

So to do this add 40 and 25 together to get 65.
Then multiply 72 by 25 to get 1800.
Then multiply 78 by 40 to get 3120.
Then add 3120 and 1800 to get 4920.
Then divide 4920 by 65 to get 75.69.
Answer = 75.69
Hope this helps!