The constant of proportionality k is 3.5
Step-by-step explanation:
Proportionality describes any relationship that is always in the same
ratio
If two quantities x and y are in proportionality, then
1. y ∝ x
2. y = k x , where k is the constant of proportionality
∵ x ⇒    6    ,    7      ,    8    ,    9
∵ y ⇒    21   ,   24.5 ,    28  ,    31.5  
∵ y ∝ x
∴ y = k x
- Use x = 6 and y = 21 to find the value of k
∵ x = 6 and y = 21
∴ 21 = k (6)
- Divide both sides by 6
∴ k = 3.5
- Use x = 7 and y = 24.5 to find the value of k
∵ x = 7 and y = 24.5
∴ 24.5 = k (7)
- Divide both sides by 7
∴ k = 3.5
- Use x = 8 and y = 28 to find the value of k
∵ x = 8 and y = 28
∴ 28 = k (8)
- Divide both sides by 8
∴ k = 3.5
- Use x = 9 and y = 31.5 to find the value of k
∵ x = 9 and y = 31.5
∴ 31.5 = k (9)
- Divide both sides by 9
∴ k = 3.5
The constant of proportionality k is 3.5
Learn more:
You can learn more about proportionality in brainly.com/question/10708697
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A = 57
45 + 12 = 57
57 - (-12) = 45
        
             
        
        
        
2. 3. 5. are correct 
1. and 4. are actually interchanged
        
             
        
        
        
Answer:
Y = 27
Step-by-step explanation:
Y * 3 = 81
Divide each side by 3
Y * 3/3 = 81/3
Y = 27
 
        
             
        
        
        
Answer:
Angle C = 45 degrees.
Angle D = 30 degrees.  
Step-by-step explanation:
Angle C = 45 + 90 = 135   180 - 135 = 45. 
Angle D = 180 - 45 = 135 (angle F)   15 + 135 = 150   180 - 150 = 30