Pears cost 2.8 yuan per kilogram, and apples and pears cost 2 kilograms each, totaling 10.4 yuan. How much is an apple per kilogram?
梨每千克2.8元，苹果和梨各要2千克，共10.4元．苹果每千克多少钱？
<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>