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

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EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12

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

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

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

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–

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

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 –

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 + –

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 –

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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.

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.

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.

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.

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

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

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.

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