A rectangular vegetable field has (7/8) hectares, (1/2) is used to grow rice, (1/4) is used to grow wheat, and the rest is used to grow vegetables. What percentage is used for growing vegetables?
一块长方形菜地有(7/8)公顷，种水稻用去(1/2)，种小麦用去(1/4)，其余种蔬菜，种蔬菜占几分之几？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>