Answer:
The cost of spoon is £1.84 and therefore the cost of one knife is £5.52.
Given :
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A knife is 3 times the cost of the spoon.
- 9 spoons and 12 knives costs £82.80.
Solution :
- 
This question is solve by creating a linear equation and linear equations are nothing but yet another subset of "equations".
- Linear calculations that requires more than one variable can be done with the help of linear equations.
- The standard form of a linear equation in one variable is ax + b = 0.
Now let x be the cost of spoon. Than the cost knife is 3x. It is given that 9 spoons and 12 knives costs £82.80.
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Therefore the cost of 1 knife = 5.52
Step-by-step explanation:  
 
        
             
        
        
        
Answer:
I dont understand that sorry
 
        
                    
             
        
        
        
<span>B. Carbon dioxide gas in air </span>
        
             
        
        
        
Answer:
x = 60
Step-by-step explanation:
t = 
15 = k/68 
k=1020
~~~~~~~~~~~
17 = 1020/x
x = 1020/17
x = 60
 
        
             
        
        
        
40°, 60° and 80°
sum the parts of the ratio 2 + 3 + 4 = 9
The sum of the angles in a triangle = 180°
Divide 180 by 9 to find one part of the ratio
 = 20° ← 1 part of the ratio
 = 20° ← 1 part of the ratio
2 parts = 2 × 20 = 40°
3 parts = 3 × 20 = 60°
4 parts = 4 × 20 = 80°
The angles in the triangle are 40°, 60° and 80°