Among the numbers greater than 20, what is the sum of all the numbers whose quotient and remainder are equal when divided by 6?
比20大的数中，所有被6除，商与余数相等的数的和是多少．
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 + 3</gadget>
<output>21</output>

<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<gadget id="calculator">24 + 4</gadget>
<output>28</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<gadget id="calculator">30 + 5</gadget>
<output>35</output>

<gadget id="calculator">21 + 28 + 35</gadget>
<output>84</output>

<result>84</result>