answer for 1a: 0.40, which is 40 cents.
what you need to do is you need to divide the amount of money of the drink which is £3.20, by the quantity of the drink which is 8, since £3.20 is the total amount of money for 8 cans.
£3.20 divided by 8 is 0.4, which logically would mean in your question it calculates to 40 cents.
another proof that the answer is 40 cents is when you multiply 0.40 by 8, it calculates to 3.2, which would mean in your question it calculates to £3.20 in total.
the answer to 1a is 40 cents.
answer for 1b: 0.35, which is 35 cents.
same thing as the first question, you need to divide the total amount of money of the drink which is £5.25, by the quantity of the drink which is 15, to calculate the actual price of the drink.
5.25 divided by 15 calculates to 0.35.
as said, the proof that the answer is right is if you multiply 0.35 by 15, it will calculate to 5.25.
the answer to 1b is 35 cents.
answer for 1c: the best value is shop A, because we have worked out that shop A sells the drink for 40 cents, and shop B sells the drink for 35 cents. therefore, shop A gets 5c more profit than shop B.