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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+ 2.1211.92
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.
