1. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12

2. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12

3. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92

4. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65

5. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65 8.00 1.65–

6. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65 8.00 –1.65 6.35

7. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65 8.00 1.65 6.35 c.8.75 + 6.394 –

8. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65 8.00 1.65 6.35 c.8.75 + 6.394 8.750 6.394 + –

9. EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12 9.80 + 2.12 11.92 b. 8 – 1.65 8.00 1.65 6.35 c.8.75 + 6.394 8.750 6.394 + 15.144 –

10. EXAMPLE 2 Evaluating Algebraic Expressions Evaluate when 20 x – x = 4.71.

11. EXAMPLE 2 Evaluating Algebraic Expressions Evaluate when 20 x – x = 4.71. 20 x = 20 4.17 Substitute 4.71 for x. ––

12. EXAMPLE 2 Evaluating Algebraic Expressions Evaluate when 20 x – x = 4.71. 20 x = 20 4.17 Substitute 4.71 for x. –– Subtract. = 15.29

13. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs

14. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.

15. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices. $1.30 $1.20 $3.70

16. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70

17. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70 $1.30 $3.70 $1.20

18. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70 $5$5 $1.30 $3.70 $1.20

19. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70 $2.40 $1.30 $3.70 $1.20 $5$5

20. Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70 $7.40 $1.30 $3.70 $1.20 $5$5 $2.40

21. ANSWER Using Mental Math to Add Decimals Find the total cost for a sweet roll that costs $1.30, two hard rolls that cost $1.20 each, and a coffee cake that costs $3.70. EXAMPLE 3 Bakery costs STEP 1 List the prices.STEP 2 Rearrange and group pairs of prices. $1.30 $1.20 $3.70 $7.40 The bakery goods will cost $7.40. $1.30 $3.70 $1.20 $5$5 $2.40

22. Evaluate the expression when x=5.82 and y=9.1. GUIDED PRACTICE for Example 1, 2 and 3

23. GUIDED PRACTICE 1. 4.7 + x = for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1.

24. GUIDED PRACTICE 1. 4.7 + x = 4.7 + 5.82 = 10.52 for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1.

25. GUIDED PRACTICE 1. 4.7 + x = 4.7 + 5.82 = 10.52 12.56 – y = 2. for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1.

26. GUIDED PRACTICE 1. 4.7 + x = 4.7 + 5.82 = 10.52 12.56 – y = 12.56 – 9.1 2. = 3.46 for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1.

27. GUIDED PRACTICE 1. 4.7 + x = 4.7 + 5.82 = 10.52 12.56 – y = 12.56 – 9.1 2. = 3.46 3. y – x = for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1.

28. GUIDED PRACTICE 1. 4.7 + x = 4.7 + 5.82 = 10.52 12.56 – y = 12.56 – 9.1 2. = 3.46 3. =3.28 for Example 1, 2 and 3 Evaluate the expression when x=5.82 and y=9.1. y – x = 9.1 – 5.82

29. GUIDED PRACTICE 4.Electronics Costs Find the total cost for a pair of headphones that costs $19.75, two compact disks that cost $11.50 each, and a pack of batteries that costs $4.25. for Example 1, 2 and 3

30. GUIDED PRACTICE The total cost is $47.ANSWER for Example 1, 2 and 3 4.Electronics Costs Find the total cost for a pair of headphones that costs $19.75, two compact disks that cost $11.50 each, and a pack of batteries that costs $4.25.