Mom goes to the vegetable market to buy vegetables, cabbage is 1.8 yuan/kg, and the price of potatoes is 1.5 times that of cabbage. How much more expensive is the unit price of potatoes than cabbage?
妈妈去菜市场买菜，白菜1.8元/千克，土豆的价格是白菜的1.5倍，土豆单价比白菜贵多少钱？
<gadget id="calculator">1.5 - 1</gadget>
<output>0.5</output>

<gadget id="calculator">1.8 * 0.5</gadget>
<output>0.9</output>

<result>0.9</result>