Answer: it is 0.
Step-by-step explanation:
 
        
             
        
        
        
Answer:
   f^-1(x) = (x -14)/10
Step-by-step explanation:
You can find the inverse function by solving for y:
   x = f(y)
Here, that is ...
   x = 10y +14 . . . . . use the definition of f(y)
   x -14 = 10y . . . . . . subtract 14
   (x -14)/10 = y . . . . divide by the coefficient of y
So, your inverse function is ...
   f^-1(x) = (x -14)/10
 
        
             
        
        
        
Divide total bought by 3 and multiply by 20cents:
210/3 = 70
70 x 0.20 = $14.00
Subtract the amount they paid by the amount they made:
14.00 - 6.50 = $7.50
The profit made was: $7.50