Kobayashi took the math test 7 times, and scored 77 points for the first time, and each time after that, he got 3 points more than the previous one. The math teacher calculated his average score as his final score. What is his final score.
小林接受7次数学考试，第一次获得77分，以后每次都比前一次多3分，数学老师计算他的平均分作为他的最终成绩．他的最终成绩是多少分．
<gadget id="calculator">77 + 3</gadget>
<output>80</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">77 + 6</gadget>
<output>83</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">77 + 9</gadget>
<output>86</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">77 + 12</gadget>
<output>89</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">77 + 15</gadget>
<output>92</output>

<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<gadget id="calculator">77 + 18</gadget>
<output>95</output>

<gadget id="calculator">77 + 80 + 83 + 86 + 89 + 92 + 95</gadget>
<output>602</output>

<gadget id="calculator">602 / 7</gadget>
<output>86</output>

<result>86</result>