The text book store sold a combined total of 326 history and chemistry textbooks in a week. The number of chemistry textbooks sold was 86 less than the number of history textbooks sold. How many textbooks of each type was sold?

The sentence

"The Number of Chem textbooks sold is 86 less than the number of History textbooks"

This seems to be the confusing part.

Now look at it this way...

'If CHM text is 86 less than History text... It also means that History Text is 86 More than CHM'

This expression can be written as

Let History Text be "H"

Let CHM text be "C"

C - 86 = H

or

C=H + 861

First line of this question is interpreted thus

H + C = 3262

From eqn 1... C=H+86

Substitute into Eqn 2

H + C=326

H + (H+86)=326

H+H=326-86

2H=240

H=240/2

H=120.

C=H+86

C=120+86

C=206.

This answer is correct... Why?

The key statement says .. The Number of CHM sold is 86 less than History...

Also interpreted as

The Number of CHM – 86 = History

206 - 86 =120.

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