6th Grade Math Textbook, Fundamentals

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Solve:c(10.8) 16.25

c(10.8) (10.8)16.25 (10.8)

c(10.8) 10.8 16.25 10.8

c5.45

Check:c(10.8) 16.25

5.45(10.8) 16.25

16.25 16.25 Tr u e

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1 Solve:4.86 b1.36

4.86 4.86b1.36 4.86

b3.5

Check: 4.86 b1.36

4.86 (3.5) 1.36

1.36 1.36 Tr u e

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2

To solve a subtraction equation with decimals, use the

Addition Property of Equality.

Solve:m(9.06) 8.47

m(9.06) (9.06)8.47 (9.06)

m0.59

Add 9.06

to both sides

to isolate m.

Remember:

Addition Property of Equality:

If ab, then acbc.

To subtract an integer,

add its additive inverse:

aba(b)

below sea level is negative

m(9.06) m9.06 and

m9.06 (9.06) m 0

4-12

Remember:

Subtraction Property of Equality:

If ab, then acbc.

Update your skills. See page 409 VI.

Addition and Subtraction

Equations with Decimals

Objective To apply the Subtraction Property of Equality to solve addition equations with

decimals • To apply the Addition Property of Equality to solve subtraction equations with decimals

A submersible rose 132.5 meters to reach a depth

of 367.5 meters below sea level. What was the

submersible’s original depth?

To find the original depth of the submersible, write and solve

an addition equation.

Let xoriginal depth of the submersible.

xmeters 132.5 meters 367.5 meters

To solve an addition equation with decimals, use the

Subtraction Property of Equality.

Solve: x132.5 367.5

x132.5 132.5367.5 132.5

x 500

Check:x132.5 367.5

 500 132.5 367.5 Substitute 500 for x, then simplify.

367.5 367.5 Tr u e

The submersible’s original depth was 500 meters below sea level.

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Subtract 132.5 from

both sides to isolate x.