6th Grade Math Textbook, Fundamentals

cost of tolls number of miles

cost per mile

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4-14

Key Concept

Solve Two-Step Equations

1. First, “undo” addition using
   the Subtraction Property of
   Equality, or “undo” subtraction
   using the Addition Property
   of Equality.
   2.Then “undo” multiplication
   using the Division Property
   of Equality, or “undo” division
   using the Multiplication
   Property of Equality.

Solve:2.7 1. 5q1. 8

2.7 2.71. 5q1.8 2.7



q 3

4.5

1. 5

1. 5q

1. 5 Divide both sides by to “undo” multiplication.1.5

Subtract 2.7 from both

sides to “undo” addition.

1 Check:

2.7 1. 5q1. 8

2.7 1. 5(3) 1.8

2.7 4.5 1.8 Simplify.

1.8 1.8 Tr u e

?



?

 Substitute

3 for q.

Solve: 3.50 1.75m10.15

3.50 3.501.75m10.15 3.50

1.75m6.65 Simplify.



m3.8

Check:3.501.75m10.15

3.50 1.75(3.8) 10.15

3.50 6.65 10.15 Simplify.

10.15 10.15 Tr u e

So Lisa’s taxi ride was 3.8 miles long.

Substitute 3.8 for m

in the original equation.

6.65

1.75

1.75m

1.75

?

?

Use the Division Property

of Equality to

“undo” multiplication.

Use the Subtraction

Property of Equality

to “undo” addition.

Solve Two-Step Equations

with Decimals

Objective To solve two-step algebraic equations containing decimals by applying the

appropriate properties of equality

Tom’s Taxi Service charged Lisa $3.50 for tolls and

$1.75 a mile. Lisa’s ride in a Tom’s Taxi cost $10.15.

How many miles was her taxi cab ride?

To find the number of miles for Lisa’s cab ride, write and

solve an equation. When you solve an equation involving

more than one operation, apply the appropriate properties

of equality using inverse operations to isolate the variable.

Let mthe number of miles for Lisa’s cab ride.

Equation: 3.50 1.75m10.15 total cost