There is a wheat field and a vegetable field. Half of the vegetable field and 1/3 of the wheat field add up to 13 mu. Half of the wheat field and 1/3 of the vegetable field add up to 12 mu, so how many acres is the vegetable field?
有一块麦地和一块菜地，菜地的一半和麦地的(1/3)合起来是13亩．麦地的一半和菜地的(1/3)合起来是12亩，那么菜地有多少亩．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) + (1/3)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">25 / (5/6)</gadget>
<output>30</output>

<gadget id="calculator">39 - 30</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>