At the boy of notebooks in a cage is 15 more, than in a ruler. How much at him notebooks if notebooks in a cage are 4 times more, than in a ruler?

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Let notebooks in a ruler was the X pieces, then notebooks in a cage was (X+15). On a statement of the problem we will work out and we will solve the equation. 4*X=X+15 4X=X+15 4X-X=15 3X=15 X=15:3 X=5 Was 5 notebooks in a ruler. Notebooks in a cage (5+15)=20 notebooks. In total notebooks of 20+5=25 notebooks. ANSWER: 25 notebooks.
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