Zhang Hua took 10 yuan, bought a pencil case and spent 3.5 yuan, how much money is left.
张华拿了10元钱，买了一个文具盒用去3.5元，还剩下多少元．
<gadget id="calculator">10 - 3.5</gadget>
<output>6.5</output>

<result>6.5</result>