Uncle Wang donated money to build "Hope Primary School" for children in the earthquake-stricken areas. It is planned to build the teaching building on a rectangular open space with a perimeter of 480m. It is known that the open space is 140m long. How many hectares does it have?
汪叔叔捐款给地震灾区的孩子们建"希望小学"．现规划把教学楼建在一块周长为480m长方形空地上，已知空地长140m，它的面积是多少公顷？
<gadget id="calculator">480 / 2</gadget>
<output>240</output>

<gadget id="calculator">240 - 140</gadget>
<output>100</output>

<gadget id="calculator">1 * 10_000</gadget>
<output>10_000</output>

<gadget id="calculator">100 / 10_000</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">140 * (1/100)</gadget>
<output>7/5 = around 1.4</output>

<result>7/5 = around 1.4</result>