Answer:
18 miles driven in a week
Step-by-step explanation:
a unit rate is x/1, x being 18 miles and 1 being 1 week
 
        
             
        
        
        
Simply add up all.
4  1/2  +    6  2/3  + 9  1/4
(4 + 6 + 9) +    1/2  + 2/3 + 1/4
19                    6/12 + 8/12 + 3/12 = (6+8+3)/12 = 17/12
19      17/12
 
19       1 5/12
19 + 1  5/12
= 20   5/12
20   5/12    yards was purchased.  
        
                    
             
        
        
        
4.
b^-2-x^-2/b^-1+x^-1
b^-2/b^-1=b^-1
x^-2/x^-1=x^-1
As a result, the simplest form is:
b^-1-x^-1. Hope it help!
        
                    
             
        
        
        
The correct answer is b
a thanks and a brainliest would be appreciated :)