Tomato sauce

This task is about working out the best price.
This table shows the prices for all the different types of tomato sauce and container sizes available at a supermarket.   
illustration: bottle of tomato sauce
 
Brand
Size of Container 
  250 ml 500 ml 750 ml 1 Litre (1000 ml)

Crest

$2.20

$3.95

$6.45

$9.00

Acorn

$1.90

$4.05

$6.25

$7.90

Watkins

$2.25

$4.55

$6.70

$9.20

 
 
a)
 
   
 
If Petra chose a 500 ml container, which brand would be the best value for money?
 
__________
 
b)
Karen bought some 250 ml bottles of Watkins tomato sauce for $2.25 a bottle.
 
How much would a litre cost if she bought several of these bottles?   $ __________
 
c) Joseph bought some 750 ml bottles of Crest tomato sauce that each cost $6.45.
 
 
i) 
 
ii)
How many bottles would he need to buy to have 3 litres of sauce?   __________
 
How much would each litre of sauce cost him?   $ __________
 
d)
To get the best value for money, you should buy the _______________ brand
 
of sauce in a __________ ml container.