Zhang Liang wants to buy a little book with a price of 3.90 yuan. He can buy one book by adding 0.80 yuan to his existing money, but he only bought a book with a price of 1.50 yuan. How much money does he have left?
张亮想买一本价格为3.90元的小人书，他现有的钱再添上0.80元正好买一本，但他只买了一本1.50元的书，他剩下多少钱？
<gadget id="calculator">3.9 - 0.8 - 1.5</gadget>
<output>1.6</output>

<result>1.6</result>