Answer:
Y=20
X=10
Step-by-step explanation:
 
        
             
        
        
        
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
Learn more about average on:
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Its b because yeah im just kidding idk im really stupid jk its b hahaha 
        
             
        
        
        
Answer:
25m
Step-by-step explanation:
Shannon's rate is 2,500m/100min. Simplifying, we see that this is equal to 25m/1min.
So, she walks 25 m in one minute.
 
        
             
        
        
        
Before we do any solving, we need to simplify both sides.
On the left, we can simplify -2x + 3x - 5 to x - 5.
On the right, we can simplify 6 - 21 to -16.
So we have x - 5 = -16.
Solving from here, we add 5 to both sides to get x = -11.