There are 127 children in the third grade going on a spring outing, 70 of them bring mineral water, 80 of them bring fruit, and each of them brings at least one piece. How many people in the third grade bring both mineral water and fruit?
三年级有127个小朋友去春游，带矿泉水的有70人，带水果的有80人，每人至少带一样．三年级既带矿泉水又带水果的有几人？
<gadget id="calculator">70 - 127</gadget>
<output>-57</output>

<gadget id="calculator">80 + (-57)</gadget>
<output>23</output>

<result>23</result>