To make a batch of toys, the original plan was to produce 80 per day, but the actual production was 20 more per day than the original plan. As a result, the task was completed one day ahead of schedule. How many toys were originally planned to be produced?
做一批玩具，原计划每天生产80个，实际每天比原计划多生产20个，结果提前1天完成任务，原计划要生产多少个玩具？
<gadget id="calculator">20 - 80</gadget>
<output>-60</output>

<gadget id="calculator">80 + (-60)</gadget>
<output>20</output>

<gadget id="calculator">80 / 20</gadget>
<output>4</output>

<gadget id="calculator">100 * 4</gadget>
<output>400</output>

<result>400</result>