On the eve of the Spring Festival, a rich man donated a sum of money to the gang of beggars. At the beginning, he planned to give each person 100 yuan, but the result was 350 yuan. He decided to give each person an extra 20 yuan. At this time, 5 beggars came from other places. If each of them got the same amount of money as the other beggars, the rich man would need to add another 550 yuan. How many beggars there were.
春节前夕，一富翁向丐帮帮众施舍一笔钱财．一开始他准备给每人100元，结果剩下350元．他决定每人多给20元．这时从其它地方又闻讯赶来了5个乞丐，如果他们每个人拿到的钱也和其它乞丐一样多，富翁还需要再增加550元．原有多少名乞丐．
<gadget id="calculator">100 + 20</gadget>
<output>120</output>

<gadget id="calculator">120 * 5</gadget>
<output>600</output>

<gadget id="calculator">550 - 600</gadget>
<output>-50</output>

<gadget id="calculator">350 + (-50)</gadget>
<output>300</output>

<gadget id="calculator">300 / 20</gadget>
<output>15</output>

<result>15</result>