A. Add up all of her scores together:
20 + 40 + 40 + 40 + 60 + 60 + 60 + 60 + 80 + 80 + 80 + 80 + 100 = 800
Or you could do multiplication, 4 example, she had 3 scores of 40, so you could do 3(40)
20 + 3(40) + 4(60) + 4(80) + 100 = 800
B. She has:
20 - 1 score
40 - 3 scores
60 - 4 scores
80 - 4 scores
100 - 1 score She took a total of 13 quizzes since she has a 13 scores
C. (this is basically the mean score)
To find the mean score/average,
you add up all of the scores, then divide the total of her scores by the number of quizzes/scores she had
800 ÷ 13 = 61.5384615385
(idk if you leave it as a fraction, or if you have to round)