Lan Lan goes to the store to buy a Hero brand pen. If she buys a pen worth 15.4 yuan, there is still a difference of 0.8 yuan. She has to buy a pen worth 8.9 yuan. How much money is left?
兰兰到商店买英雄牌钢笔，如果买15.4元的钢笔，还差0.8元，她只好买了8.9元的钢笔，还剩多少钱？
<gadget id="calculator">15.4 - 0.8 - 8.9</gadget>
<output>5.7</output>

<result>5.7</result>