The cafeteria bought 50 kilograms of rice and 50 kilograms of flour, and the total cost was 258.5 yuan. The rice was 2.9 yuan per kilogram, and how much was the flour per kilogram?
食堂买来大米和面粉各50千克，共花去258.5元钱，大米每千克2.9元，面粉每千克多少元？
<gadget id="calculator">258.5 / 50</gadget>
<output>5.17</output>

<gadget id="calculator">5.17 - 2.9</gadget>
<output>2.27</output>

<result>2.27</result>