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## Ignore words

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subtract 27

To "undo" add 27, I would...

subtract 4

To "undo" add 4, I would...

add 65

To "undo" subtract 65, I would...

add 37

To "undo" subtract 37, I would...

divide by 10

To "undo" multiply by 10, I would...

divide by 7

To "undo" multiply by 7, I would...

multiply by 9

To "undo" divide by 9, I would...

multiply by 23

to "undo" divide by 23, I would...

Equation

A mathematical sentence that contains an equals sign

Variable

an alphabetic character representing a number, called the value, which is either arbitrary or not fully specified or unknown. It is usually a letter like x or y.

equivalent

Equal to

inverse operation

Operations that undo each other

Subtraction

to take a quantity away from another

Addition

to join two or more quantities

Division

process of breaking a quantity into equal parts

Multiplication

process of repeated addition

inequality

A mathematical sentence that shows the relationship between quantities that are not equivalent

<

Less than

>

Greater than

≤

Less than or equal to

≥

Greater than or equal to

≠

Not equal to

x+9-9

x+9

x-7+7

x-7

-7

What is the inverse of +7?

plus 15

What is the inverse of minus 15?

divide by 6

What is the inverse of times 6?

minus 4

What is the inverse of plus 4?

times 3

What is the inverse of divided by 3?

undoes the given operation

What does the inverse operation do?

add 19

to undo negative 19

add 225

to undo negative 225

divide 500

to undo 500

divide 9,000

to undo 9,000

multiply 5

to undo 5

multiply 9,000,000

to undo 9,000,000