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Hello:

Why are 100 and 40 the only amounts subtracted from the calculation below? Why not subtract the two 4's as well? The two products (400 & 160# can be subtracted and get the 240 as well.

100 X 4 = 400

-40 X 4 = 160

-------------

60 X 4 = 240

The above is a confusing way to indicate #100 - 40) X 4 = 240.

I thank you for your follow-up reply.

What they are trying to show is that (100-40) x 4 is the same as 100*4 - 40*4.

See, on the left side, they too 100 - 40 and got 60, then multiplied by 4 and got 240.

On the right side, they multiplied by 4 first.

They took 100 * 4 and got 400, then -40*4 and got -160.

It can then be seen that 400 - 160 is 240.

Just think of

100

-40

-----

60, and that is the basic problem they are showing.

----------------------------------------------------------------------------------------------

If we multiplied each term (100, -40, and 60) by 2,

we'd get 100*2 = 200, -40*2 = -80, and 60*2 =120.

This would give

200

-80

-----

120, and that can be seen to be correct.

----------------------------------------------------------------------------------------------

If we multiplied each term (100, -40, and 60) by 7,

we' get 100*7 = 700, -40*7 = -280, and 60*7 = 420.

This would give

700

-280

------

420, and that can be seen to be correct as well.

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