A piece of land (3/7) hectares, of which (1/5) is planted with corn, (3/8) is planted with peanuts, and the rest is planted with potatoes. What percentage of the land is planted with potatoes?
一块地(3/7)公顷，其中(1/5)种玉米，(3/8)种花生，其余种土豆，种土豆的面积占这块地的几分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(1/5) + (3/8)</gadget>
<output>23/40 = around 0.575</output>

<gadget id="calculator">1 - (23/40)</gadget>
<output>17/40 = around 0.425</output>

<result>17/40 = around 0.425</result>