A, B, and C water 91 pots of flowers, A waters 68 pots, B waters 64 pots, and C waters 55 pots. At least how many pots have been watered by all three.
甲乙丙三人浇91盆花，甲浇了68盆，乙浇了64盆，丙浇了55盆，三人都浇过的至少有多少盆．
<gadget id="calculator">68 + 64 + 55</gadget>
<output>187</output>

<gadget id="calculator">91 * 2</gadget>
<output>182</output>

<gadget id="calculator">187 - 182</gadget>
<output>5</output>

<result>5</result>