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Presentation by Howard C. McAllister. Copyright 1996
For a lesson plan using this example click here.

Problem: Mary has twice as many apples as
Bill, who has 3 times as many as Joe. If Joe has 4 apples,
how many does Mary have?

(Use Mary's, Bill's and Joe's for the variables.)
The problem asks for the number of
apples Mary has. The problem statement
tells us that she has twice as many as Bill.

This equation requests
information about the number of apples
Bill has. The problem states that

The equation just written requests
information about Joe's. The value of Joe's
is provided by the problem statement.
Written in equation form it is
The result of substitution is
----See TIP
The result of doing the arithmetic is


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COPY and PASTE can be used to effect substitution reliably.
Copy the top equation and paste it in the substitution box.
Then copy the right side of each indented equation, starting with the first one, and paste them on the appropriate symbols in the substitution box.
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