When Liangliang came home, Lili and the puppy ran towards him at a distance of 500 meters from the door. After reaching Liangliang, he kept going back and forth between them at the same speed. When Liangliang and Lili were 20 meters apart, how many meters did the puppy run in total?
亮亮回家，在距家门500米处，丽丽和小狗一齐向他跑来，亮亮和丽丽的速度都是每分钟60米，小狗的速度是每分钟220米，小狗遇到亮亮后以同样的速度不停的往返于他俩之间，当亮亮和丽丽相距20米时，小狗一共跑了多少米？
<gadget id="calculator">500 - 20</gadget>
<output>480</output>

<gadget id="calculator">60 + 60</gadget>
<output>120</output>

<gadget id="calculator">480 / 120</gadget>
<output>4</output>

<gadget id="calculator">220 * 4</gadget>
<output>880</output>

<result>880</result>