The money my father brought was just enough to buy 8 kilograms of apples. Now I bought 4.5 kilograms, and there is 10.5 yuan left. How much is a kilogram of apples?
爸爸带的钱刚好能买8千克苹果，现在买了4.5千克，还剩10.5元，每千克苹果多少元？
<gadget id="calculator">8 - 4.5</gadget>
<output>3.5</output>

<gadget id="calculator">10.5 / 3.5</gadget>
<output>3</output>

<result>3</result>