Qingshan Primary School has a rectangular flowerbed, 12 meters long. When building the campus, the length of the flower bed was increased by 4 meters, so the area was increased by 20 square meters. What is the area of the garden now? (Draw diagrams first, then answer)
青山小学有一块长方形花圃，长12米．在修建校园时，把花圃的长增加了4米，于是面积增加了20平方米．现在这个花圃的面积是多少平方米？(先画图分析，再解答)
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">12 + 4</gadget>
<output>16</output>

<gadget id="calculator">5 * 16</gadget>
<output>80</output>

<result>80</result>