Abraham's physics class has 40 students, and his class had an average (arithmetic mean) score of 75 on the midterm. anita’s physics class has 20 students, and her class had an average score of 81 on the same midterm. what was the average score of all the students in both physics classes on the midterm?

Average=(scores total)/(number of scores)

We are given two averages and two numbers of students so we can calculate the total scores in each class..

75=Ab/40, so the sum of Abraham's class scores is 40(75)=3000 and similarly
81=An/20, so the sum of Anita's class scores is 20(81)=1620

Now we know the total score for all the students is 3000+1620=4620

And we also know that there are a total fo 40+20=60 students, so the overall average for all the students is

a=4620/60=77

Uneed to add them up 27+18+23=68