Increase and decrease a quantity by a given percentage, using mental, written and calculator methods

1. Toffee profit: Calculate a sum given original expenditure and percentage profit
2. A long trip home: Calculate a total from a percentage
3. A big bill: Calculate a total from a percentage
4. Well-watered campers: Calculate a total from a percentage
5. A tasty sweetener: Calculate a percentage increase of a quantity or number
6. As time goes by : Calculate the first quantity given a final figure and percentage increase.
7. Footy fever: Calculate a new price given the old price and percentage increase
8. Percentage Wise: 560% of 12 litres=?
9. Percentage Wise: Increase 320 by 80%
10. Percentage Wise: Increase 4L by 1%
11. Percentage Wise: Decrease 3L by 60%
12. Fast shoe shuffle: Calculate prices using percentage increase and decrease