A batch of woolen sweaters was shipped from the store, and 20 pieces were sold every day on average, and 20 pieces remained unsold after 5 days. How many sweaters are there in this batch?
商店运来一批羊毛衫，平均每天卖出20件，5天后还有20件没有卖出．这批羊毛衫共有多少件？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 + 20</gadget>
<output>120</output>

<result>120</result>