Answer:
14
Step-by-step explanation:

 
        
             
        
        
        
Step-by-step explanation:
there is no reason in maths only the method
 
        
             
        
        
        
Answer:
x=−y−1
Step-by-step explanation:
y=−x−1
Step 1: Flip the equation.
−x−1=y
Step 2: Add 1 to both sides.
−x−1+1=y+1
−x=y+1
Step 3: Divide both sides by -1.
−x
−1
=
y+1
−1
x=−y−1
 
        
             
        
        
        
I think it would be 7 miles per gallon. Just do Miles/Gallons per week.