Yucai Primary School participated in the city sports meeting. There were 11 participants in the fourth grade, 6 less than the fifth grade. The number of participants in the sixth grade is twice the total number of participants in the fourth and fifth grades. How many people in the sixth grade participate in the city sports meeting?
育才小学参加市运动会．四年级有11人参加，比五年级少6人．六年级参加的人数是四、五年级参加的总人数的2倍．六年级有多少人参加市运动会？
<gadget id="calculator">11 + 6 + 11</gadget>
<output>28</output>

<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<result>56</result>