**READING: II §2 O3**
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II §2 O2

*begin quote ita***"**

*CHAPTER II* [:]
**
The Real Number System
**

Please get the book and read along. topic index contents

by the definition of subtraction | |||

by F10 | |||

by the distributivity of muliplication over addition | |||

by F10 | |||

by the associativity of addition | |||

by the commutativity of addition | |||

by the associativity of addition | |||

by the definition of subtraction | |||

by the commutativity of addition | |||

by the associativity of addition | |||

by the definition of subtraction | |||

Consequently, the sum (a-b) + (c-d) is in because of the order property.

Finally, by the chain of equal signs, we have the desired result: (a+c)-(b+d)