Add the same integer to the numerator and denominator of (1/13) at the same time, the new fraction obtained is equal to (1/2), find this number.
将(1/13)的分子和分母同时加上一个相同的整数，得到的新分数与(1/2)相等，求这个数．
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">12 / 1</gadget>
<output>12</output>

<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<result>11</result>