Aunt Wang bought 3 kilograms of oranges and 4 kilograms of apples and shared them for 32.4 yuan. Oranges are 3.6 yuan per kilogram, how much are apples per kilogram?
王阿姨买了3千克橘子和4千克苹果，共用去32.4元．橘子每千克3.6元，苹果每千克多少元？
<gadget id="calculator">3.6 * 3</gadget>
<output>10.8</output>

<gadget id="calculator">32.4 - 10.8</gadget>
<output>21.6</output>

<gadget id="calculator">21.6 / 4</gadget>
<output>5.4</output>

<result>5.4</result>