Find the area of equilateral triangle with side a. will give brainliest if correct! explain aswell

You can just use the specific formula for equilateral triangle to find the area, but I'll derive it for you if need it:

Brooke needs to get a 98 on the final to get an average of 80.
So you know that the total of the five given score is 382 by adding all the scores.
Now you multiply the average, 80 by 6 for the total of six tests including the final which is 480
Then you subtract 480-382 to find your answer.