3个数相加等于27的有多少个

75组解，大于等于0的。
{0, 0, 27}, {0, 1, 26}, {0, 2, 25}, {0, 3, 24}, {0, 4, 23}, {0, 5, 22}, {0, 6, 21}, {0, 7, 20}, {0, 8, 19}, {0, 9, 18}, {0, 10, 17}, {0, 11, 16}, {0, 12, 15}, {0, 13, 14}, {1, 1, 25}, {1, 2, 24}, {1, 3, 23}, {1, 4, 22}, {1, 5, 21}, {1, 6, 20}, {1, 7, 19}, {1, 8, 18}, {1, 9, 17}, {1, 10, 16}, {1, 11, 15}, {1, 12, 14}, {1, 13, 13}, {2, 2, 23}, {2, 3, 22}, {2, 4, 21}, {2, 5, 20}, {2, 6, 19}, {2, 7, 18}, {2,8, 17}, {2, 9, 16}, {2, 10, 15}, {2, 11, 14}, {2, 12, 13}, {3, 3, 21}, {3, 4, 20}, {3, 5, 19}, {3, 6, 18}, {3, 7, 17}, {3, 8, 16}, {3,9, 15}, {3, 10, 14}, {3, 11, 13}, {3, 12, 12}, {4, 4, 19}, {4, 5,18}, {4, 6, 17}, {4, 7, 16}, {4, 8, 15}, {4, 9, 14}, {4, 10, 13}, {4, 11, 12}, {5, 5, 17}, {5, 6, 16}, {5, 7, 15}, {5, 8, 14}, {5, 9, 13}, {5, 10, 12}, {5, 11, 11}, {6, 6, 15}, {6, 7, 14}, {6, 8, 13}, {6, 9, 12}, {6, 10, 11}, {7, 7, 13}, {7, 8, 12}, {7, 9, 11}, {7, 10, 10}, {8, 8, 11}, {8, 9, 10}, {9, 9, 9}

解：（一）无数个。
1.8+9+10=27
2.7+8+11=27
3......
（二）三个单数相加，可以是相同数。就一个。
9+9+9=27

三个加数都是27

20+20+7=27