The convenience store bought back a batch of grain, sold 4.25 tons for the first time, sold 3.78 tons for the second time, and left 15.75 tons. How many tons of this batch of grain are there?
便民粮店购回一批粮食，第一次卖了4.25吨，第二次卖了3.78吨，还剩15.75吨，这批粮食共有多少吨？
<gadget id="calculator">4.25 + 3.78 + 15.75</gadget>
<output>23.78</output>

<result>23.78</result>