The school plans to afforest a 300m**2 vacant land, first set aside 20% of the total area to plant trees, and the rest to plant flowers and grasses at a ratio of 2:3. How big is the grass area?
学校计划绿化一块300m**2的空地，先划出总面积的20%种树，剩余的按2：3种花和草．草地的面积有多大？
<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">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">300 * (4/5) * (3/5)</gadget>
<output>144</output>

<result>144</result>