The ratio of numerator and denominator of a fraction before division is 2:5, the sum of numerator and denominator is 56, what is the fraction before division.
一个分数约分前分子分母的比是2：5，分子与分母的和是56，约分前的分数是多少．
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">56 * (2/7)</gadget>
<output>16</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">56 * (5/7)</gadget>
<output>40</output>

<gadget id="calculator">16 / 40</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>