A bag of milk powder is 21 yuan more expensive than a bag of biscuits. They are 41 yuan in total. How much is a bag of milk powder?
一袋奶粉比一袋饼干贵21元，它们一共是41元，一袋奶粉多少钱？
<gadget id="calculator">41 + 21</gadget>
<output>62</output>

<gadget id="calculator">62 / 2</gadget>
<output>31</output>

<result>31</result>