EXAMPLE 1 Adding and Subtracting Decimals a. 9.8 + 2.12

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+ 2.1211.92

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

8.001.65–

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

8.00– 1.65

6.35

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

8.001.656.35

c. 8.75 + 6.394

–

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

8.001.656.35

c. 8.75 + 6.394

8.7506.394+

–

EXAMPLE 1 Adding and Subtracting Decimals

a. 9.8 + 2.12

9.80+ 2.1211.92

b. 8 – 1.65

8.001.656.35

c. 8.75 + 6.394

8.7506.394+

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$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 grouppairs of prices.

$1.30$1.20$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 grouppairs of prices.

$1.30$1.20$1.20$3.70

$1.30$3.70$1.20$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 grouppairs of prices.

$1.30$1.20$1.20$3.70

$5$1.30$3.70$1.20$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 grouppairs of prices.

$1.30$1.20$1.20$3.70

$2.40

$1.30$3.70$1.20$1.20

$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 grouppairs of prices.

$1.30$1.20$1.20$3.70

$7.40

$1.30$3.70$1.20$1.20

$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 grouppairs of prices.

$1.30$1.20$1.20$3.70

$7.40

The bakery goods will cost $7.40.

$1.30$3.70$1.20$1.20

$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.