18.
18 x 3 - 14 = 40
.
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Evaluating a function means to plug the required value, substituting every x occurrence with that value.
So, you have

 
        
             
        
        
        
Answer:
15
Step-by-step explanation:
 
        
             
        
        
        
Starting with ...

1) Multiply by the inverse of the coefficient multiplying the sum with M, then subtract m.

2) Multiply by g/T²

 
        
             
        
        
        
Set a proportion which is 42/5 = x/12 cross multiply and divide by 5 which gives you $100.8 dollars