Ao Zebra, Xiaomei, and Ou Ou watered 100 potted flowers. Ao Zebra watered 78 pots, Xiaomei watered 68 pots, and Ou Ou watered 85 pots. So, at least how many potted flowers have been watered three times.
奥斑马、小美、欧欧给100盆花浇水．奥斑马浇了78盆，小美浇了68盆，欧欧浇了85盆．那么，至少有多少盆花被浇了三次水．
<gadget id="calculator">78 + 68 + 85</gadget>
<output>231</output>

<gadget id="calculator">100 * 2</gadget>
<output>200</output>

<gadget id="calculator">231 - 200</gadget>
<output>31</output>

<result>31</result>