Teacher Zhang took 100 yuan to the supermarket to buy 4.5 kilograms of eggs at 9.7 yuan per kilogram, and then bought 2.3 kilograms of apples, leaving 36.8 yuan. How much is an apple per kilogram?
张老师拿了100元去超市买每千克9.7元的鸡蛋4.5千克，然后又买了2.3千克苹果，还剩36.8元．每千克苹果多少元？
<gadget id="calculator">9.7 * 4.5</gadget>
<output>43.65</output>

<gadget id="calculator">100 - 43.65 - 36.8</gadget>
<output>19.55</output>

<gadget id="calculator">19.55 / 2.3</gadget>
<output>8.5</output>

<result>8.5</result>