A5. Matej bought 12 notebooks. In the neighboring stationery store, he would have paid 20 cents more for each notebook and would have bought 3 fewer notebooks for the same amount of money. How much did Matej pay for one notebook?
(A) 35 cents
(B) 60 cents
(C) 72 cents
(D) 3 euros
(E) none of the above
A5. Let the price of a notebook before the price increase be denoted by $x$ and write the equation: $12 x=9 \cdot(x+0.20)$. The price of one notebook before the price increase was $x=0.60$ euros or 60 cents.