Uncle Zhang brought 800 yuan to buy chemical fertilizers. He bought 25 bags and left 50 yuan. How much is an average bag of fertilizer?
张大爷带了800元钱去买化肥，买了25袋还剩50元．平均每袋化肥多少元？
<gadget id="calculator">800 - 50</gadget>
<output>750</output>

<gadget id="calculator">750 / 25</gadget>
<output>30</output>

<result>30</result>