Uncle Liu brought 800 yuan to buy chemical fertilizers. He bought 16 bags at 45 yuan each. How much money is left?
刘叔叔带800元买化肥，买了16袋，每袋45元，还剩下多少元钱？
<gadget id="calculator">16 * 45</gadget>
<output>720</output>

<gadget id="calculator">800 - 720</gadget>
<output>80</output>

<result>80</result>