Aunt Wang bought 2 kilograms of apples and 2 kilograms of pears, 2.8 yuan per kilogram of pears, and a total of 10.4 yuan. How much is an apple per kilogram?
王阿姨买苹果和梨各2千克，每千克梨2.8元，一共用了10.4元．每千克苹果多少元？
<gadget id="calculator">2.8 * 2</gadget>
<output>5.6</output>

<gadget id="calculator">10.4 - 5.6</gadget>
<output>4.8</output>

<gadget id="calculator">4.8 / 2</gadget>
<output>2.4</output>

<result>2.4</result>