Fang Fang went to the store to buy a fountain pen, and he bought one for 8.5 yuan, which was a difference of 1.6 yuan, so he had to buy a pen for 5.9 yuan. The rest of the money just bought an eraser. How much is an eraser?
方方到商店买钢笔，买8.5元一支的，差1.6元，于是他只好买5.9元一支的．剩下的钱正好买一块橡皮．一块橡皮多少钱？
<gadget id="calculator">8.5 - 1.6 - 5.9</gadget>
<output>1</output>

<result>1</result>