**Video on Percentages**

Introduction to Percentages

#### Q1)

16% of 80

= 16/100 x 80

= 12 4/5

#### Q2)

7 1/2% of 125

= 7.5/100

= 44.5

#### Q3)

210% of 300

= 210/100 x 300

= 630

Decreasing and Increasing by a Percentage

#### How to Increase:

Start by making a statement saying the percentage *of* the amount

- eg: Increase $20 by 10%
- 110% of $20 (we do 110% because we are finding 110% of $20[not just 10% because that would be decreasing])

Then convert this statement into a fraction over 100

- eg: Increase $20 by 10%
- 110% of $20 = 110/100 x 20

Then solve it using a calculator!

#### How to Decrease:

Start by making a statement saying the percentage of the amount

- eg: Decrease $20 by 10%
- 90% of $20 (we do 90% because we are finding 90% of $20[not just 10% because that would be decreasing by to much & not 110% because that would be increasing])

Then convert this statement into a fraction over 100

- eg: Decrease $20 by 10%
- 90% of $20 = 90/100 x 20

Then solve it using a calculator!

Review Sheet Answers

1. 3x

2. 0.65

3. 6

4. 45

5. 0.825

6. -85

7. 3/17

8. 6.25pm

9. 0

10. 3.62

11. 9xy + 2y

12. -2x2+22x-3

13. hemisphere

14. $24

15.10a^2y^2

16. 27/2500

17. 45

18. $142.50

19. 1705.04

20. 2xy(9x-5y)

21. -1

22. 179

23.4 & 2/25

24. -31

25. 12.25 pm

26. 3600

27. 66.24

28. 129.8cm

29. $104.89cm

30. 720

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