Solve a problem by an algebraic way on production of 60 notebooks of 2 types vulgarly of 840 sheets of paper on everyone notebooks of 1 look 12 sheets were required and it the notebook of other type of 18 sheets was made how many notebooks of each look

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Notebooks on 12 sheets x (pieces) of Notebooks on 18 sheets (60 - x) pieces On a notebook on 12 sheets will go 12th (sheets) To notebooks on 18 sheets will go 18 * (60 - x) sheets. As on all notebooks of all vulgarly of 840 sheets, we will work out the equation: the 12th + 18 * (60 - x) = 840 of the 12th + 1080 - the 18th = 840 - the 6th =-1080 + 840 the 6th = 240 x = 40 are notebooks on 12 sheets 60 - x = 60 - 40 = 20 are notebooks on 18 sheets Answer: 40 notebooks on 12 sheets, 20 notebooks on 18 sheets.
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