Answer:
72%
Step-by-step explanation:
There are a total of 50 quizzes in the year
From the first 20, the student passes 60%. This makes a total of
12 passes
Out of the remaining 30 quizzes the student passes in 80% of them. This makes a total of
24 passes
Adding the two values
12 + 24 = 36
The student passes 36 quizzes out of 50.
We convert this to a percentage
%