In the love one-day donation activity, the fourth grade donated 240 yuan, the fifth grade donated twice that of the fourth grade, and the sixth grade donated 108 yuan less than the total of the fourth and fifth grades. How much is the sixth grade donation?
爱心一日捐活动中，四年级捐款240元，五年级捐款是四年级的2倍，六年级捐款比四、五年级的总数少108元，六年级的捐款多少元？
<gadget id="calculator">240 * 2</gadget>
<output>480</output>

<gadget id="calculator">240 + 480</gadget>
<output>720</output>

<gadget id="calculator">720 - 108</gadget>
<output>612</output>

<result>612</result>