Chapter tests count for 60% of the final grade. Mid-term and final
tests count for 40% of the final grade. Scores for chapter tests were
80, 50 and 69. Mid-term and final tests were 80 and 90. What is the
final grade. One of us says 73.8 and the other says 80.7


I get 73.8%. Here's how I got it:

First, find the average of the test scores: (80+50+69)/3=66.3%

Then, find the average for the midterm and the final: (80+90)/2=85%.

Now, calculate the weighted percentage: (66.3%)*0.6+(85%)*0.4= 73.8%

How does the math go to get 80.7%??