It costs Xiaoliang 1.8 yuan less to buy a pencil than to buy a notebook. Bought 10 pencils, each pencil is 0.5 yuan, bought 4 notebooks, how much is each notebook?
小亮买铅笔比买笔记本少花1.8元．买了10支铅笔，每支铅笔0.5元，买了4本笔记本，每本笔记本多少元？
<gadget id="calculator">10 * 0.5</gadget>
<output>5</output>

<gadget id="calculator">5 + 1.8</gadget>
<output>6.8</output>

<gadget id="calculator">6.8 / 4</gadget>
<output>1.7</output>

<result>1.7</result>