a) Sammie earns
  £320×4% = £12.80
each year.
Joel earns
  £420×3% = £12.60
each year.
Sammie earns the most interest.
b) Joel's interest after 5 years is 
  £12.60×5 = £63
so the total amount of money Joel will have is
  £420 +63 = £483
        
             
        
        
        
(40 min)/(5 mi) = (time)/(7 mi) . . . . . the rates are the same
(7/5)*(40 min) = time = 56 min
At the same rate, it would take Petra 56 minutes to jog 7 miles.
        
                    
             
        
        
        
It might be the first one or the second one. i said MIGHT!!