The total area of barren hills contracted by Uncle Zhang’s family is 150 hectares, of which 20% are planted with fruit trees and the rest are planted with pine trees. How many hectares are planted with pine trees?
张大伯家承包荒山总面积是150公顷，其中20%种果树，剩下的种松树．种松树的面积是多少公顷？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">150 * (4/5)</gadget>
<output>120</output>

<result>120</result>