a 
7
because 4a + 7 - 7 35 - 7
equals 4a 28
and 4a/4 28/4
equals a 7
The average score of all the students in both classes is 84.
<h3>How to calculate the average?</h3>
The class with 30 students had an average score of 80 on a test. The total score will be:
= 30 × 80
= 2400
A class with 20 students had an average score of 90 on the same test. The total score will be:
= 20 × 90
= 1800
Total scores = 2400 + 1800 = 4200
Number of students = 20 + 30 = 50
The average score will be:
= Total score / Total students
= 4200 / 50
= 84
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Answer:
D is your answer.
Step-by-step explanation:
if you do 2 numbers to the right you get 3 and now the half would go in between 3 which would make your answer 3 and one half
