Dad gave the task of writing brush characters to two brothers according to the ratio of 5:3. As a result, the elder brother wrote 1440 characters, 20% overfulfilled, and the younger brother only completed 80%. How many words did the younger brother write?
爸爸将写毛笔字任务按5：3分给了兄弟2人，结果哥哥写了1440个字，超额完成20%，弟弟只完成了80%，请问弟弟写了多少字？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1_440 / (6/5)</gadget>
<output>1_200</output>

<gadget id="calculator">1_200 / 5</gadget>
<output>240</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">240 * 3 * (4/5)</gadget>
<output>576</output>

<result>576</result>