Subtraction

I have 27 sweets and I eat 9, how many do I have left?

27 - 9 =

I take out costs me £10.79, but I only have a £20 note, how much change do I have?

20.00 - 10.79 =

I go to the pub and buy my friends a round of drinks.

The drinks total £15.27, so I give the bartender a £20 not and 27p. How much change will I receive?

I got to Primark and put lot's of clothes in my basket.....because it's cheap!!!

I buy three tops at £7.99, £11.50 and £15.75. I give the cashier two £20 notes, how much change should I receive?