Answer:
According to the sample data, we can claim that the current satisfaction rate is different from last year's. 
Step-by-step explanation:
The explanation is in the picture. 
 
        
             
        
        
        
do it step by step will it work yes
 
        
             
        
        
        
4x + 89.95 = 628.35 <== ur equation
4x = 628.35 - 89.95
4x = 538.40
x = 538.40 / 4
x = 134.60 <== the cost for each cavity filling
        
                    
             
        
        
        
Your question seems to be -7 +(1/8) -(-9) + (1/2) but then there is a decimal in front of the next -2 so that makes no sense unless that is a period before starting a new equation. You can simply type this beginning section into a calculator to get your answer of (21/8), but I have a feeling you just tried to copy and paste a test question and it did not format correctly in your question so is probably much more complicated than using a calculator. 
A better idea would be to write it in math terms instead of words, then find a common denominator so you can simplify. Writing it out in words makes it too hard for your brain to think about it in terms of math.
        
                    
             
        
        
        
Answer:
7 is the coefficient of 7y
Step-by-step explanation:
explanation in the text book pls refer TB