Mom bought 10 kilograms of rice and 8 kilograms of white flour on Sunday. It is known that the rice is 1.8 yuan per kilogram. Mom paid 50 yuan and got back 12.8 yuan. How much is it per kilogram of white flour?
妈妈星期天买大米10千克，白面8千克，已知大米每千克1.8元，妈妈付了50元，找回12.8元，每千克白面多少元？
<gadget id="calculator">1.8 * 10</gadget>
<output>18</output>

<gadget id="calculator">50 - 18 - 12.8</gadget>
<output>19.2</output>

<gadget id="calculator">19.2 / 8</gadget>
<output>2.4</output>

<result>2.4</result>